Molecular cloning and characterization of a cDNA encoding canine type VII collagen non-collagenous (NC1) domain, the target antigen of autoimmune disease epidermolysis bullosa acquisita (EBA)

Type VII collagen, the major component of anchoring fibrils, serves as tight adhesion of skin basement membrane zone (BMZ) through its amino-terminal non-collagenous (NC1) domain. The NC1 domain is targeted by autoantibodies of an acquired blistering skin disease termed epidermolysis bullosa acquisita (EBA) naturally occurring in humans and dogs. We cloned the full-length canine type VII collagen NC1 domain cDNA and delineated its molecular and immunological characteristics. The canine NC1 domain cDNA consists of 3759 nucleotides encoding for 1253 amino acids, with a molecular mass of approx. 134 kDa and a 17 amino acid signal peptide. The expression of canine type VII collagen was confirmed by Northern blot analysis and by a rabbit antibody raised against a 17 amino acid peptide deduced from canine NC1 sequence. Comparison of canine NC1 with the corresponding human sequence indicated 86.7% and 87.6% identity at the nucleotide and deduced amino acid levels respectively. The protein homology reached greater than 95% within two immunodominant epitope areas. Furthermore, human EBA autoantibodies and a rabbit anti-human NC1 cross-reacted with canine skin BMZ and the newly synthesized canine type VII collagen. The molecular and immunological identities between human and canine NC1 domains suggest that NC1 may be critical for the EBA development.

Quantitative characterization of the binding of histamine by heparin

Tissue histamine is stored in mast cell granules, presumably as a histamine-heparin complex. Heparin is a polyelectrolyte, with a fraction of its anionic charge neutralized by condensed counterions. The interaction of heparin with histamine in aqueous solution was quantitatively characterized by 1H nuclear magnetic resonance (NMR) spectroscopy. Binding constants were determined from chemical shift-pH titration data for the C2H proton of the imidazolium ring for a wide range of histamine, heparin, and Na+ concentrations. The results indicate a binding stoichiometry of 1 histamine per heparin disaccharide repeat unit. The binding is electrostatic, as indicated by the strong dependence of the binding constant on Na+ concentration. From an analysis of the binding constants using the counterion condensation theory of polyelectrolytes, it was determined that the binding of H2A2+ results in displacement of 1.72 Na+ ions from the counterion condensation volume of heparin and that H2A2+ makes 2 ionic interactions with heparin. The displacement of Na+ from the counterion condensation volume of heparin by H2A2+ was also studied by 23Na NMR. From 23Na spin-lattice relaxation time data, it was determined directly that 1.78 Na+ ions are displaced per H2A2+ bound by heparin. The results are discussed in terms of the ion exchange process which takes place when histamine is released by mast cells.

The ability of positive transcription elongation factor B to transactivate human immunodeficiency virus transcription depends on a functional kinase domain, cyclin T1, and Tat

By binding to the transactivation response element (TAR) RNA, the transcriptional transactivator (Tat) from the human immunodeficiency virus increases rates of elongation rather than initiation of viral transcription. Two cyclin-dependent serine/threonine kinases, CDK7 and CDK9, which phosphorylate the C-terminal domain of RNA polymerase II, have been implicated in Tat transactivation in vivo and in vitro. In this report, we demonstrate that CDK9, which is the kinase component of the positive transcription elongation factor b (P-TEFb) complex, can activate viral transcription when tethered to the heterologous Rev response element RNA via the regulator of expression of virion proteins (Rev). The kinase activity of CDK9 and cyclin T1 is essential for these effects. Moreover, P-TEFb binds to TAR only in the presence of Tat. We conclude that Tat-P-TEFb complexes bind to TAR, where CDK9 modifies RNA polymerase II for the efficient copying of the viral genome.

[Nasopharyngeal carcinoma and dermatomyositis (analysis of 12 cases)]

The onset relationship between dermatomyositis (DM) and malignant tumor, especially nasopharyngeal carcinoma (NPC), was approached. Approximately 90 cases of DM were admitted in the hospital. Among them 15 cases were complicated with malignant tumor of which 12 cases were complicated with NPC (account for 80% of DM with complicated carcinoma). In addition to treat these patients with prednisone and antibiotics, radiation therapy has been applied for NPC and metastasis in the neck. During the hospitalizations, one patient died, eleven patients' NPC was controlled, and the DM was completely resolved or improved. There is an obvious relationship between DM and carcinoma. DM may improve or even subside with good short term prognosis, as long as the carcinoma is controlled successfully.

Newly developed initial-flow cell filtrometer and the comparison with viscometry and ektacytometry on erythrocyte deformability

According to Hanss's initial-flow rate method, F. Liao designed a new cell filtrometer in the early 1990s. The parameters, cell initial transit time (Tc) and membrane clogging rate (CR), can be determined by a single measurement with timing accuracy of 1 ms. The new cell filtrometer has two valuable features: a button-pushing operation to control electromagnetic valves; and an autocirculation of fluid in the cell filtrometer resulting in the same volume of leading fluid. A series of comparisons of the new filtrometry with viscometry or ektacytometry shows that the instrument seems to be more sensitive in detecting subpopulations of glutaraldehyde-hardened cells and the shift of deformability for all the cells. The reproducibility of the filtrometer for different membranes made in China and the USA is reasonable (CV < 5% for Tc). Preliminary application of the filtrometer indicates that it might be useful for trial study and routine clinical application.

[Intrahepatic portal vein compliance in cirrhosis]

OBJECTIVE

To elaborate the effects of increase in portal flow on intrahepatic vein compliance with isolated perfused cirrhotic model (IPCM).

METHOD

Cirrhosis was induced by CCl(4) in 80 Wistar rats, which were divided into two groups A and B, by portal with/without hepato-artery. Portal flow was increased and hemodynamic parameters were recorded and analysed.

RESULT

In group A, compared with 1.65 +/- 0.28 kPa at basal control, portal pressure was elevated from 2.55 +/- 0.40 kPa to 3.96 +/- 0.67 kPa. Q(35)-Q(55) flow rates were raised from 35 to 55 ml/min, respectively. A correlation existed between portal flows and pressures (r = 0.985, P < 0.01). The low flow rate of 15 ml/min at Q(15) caused a irreversible model injury. A largest flow rate in IPCM was, less than in IPRL. In group B, no low flow-injury was found.

CONCLUSION

Portal vein compliance of liver is decreased markedly in cirrhotic portal hypertension, but hepatic flow is increased. There are likely some compensative relations between portal and hepato-arterial system.

Alpha-1 adrenergic receptors in liver plasma membranes of cirrhotic patients with portal hypertension: a quantitative study

OBJECTIVE

To investigate the changes of alpha-1 adrenergic receptors in cirrhotic liver and the relationship between the changes and the pathogenesis of portal hypertension.

METHODS

The concentration and affinity of alpha-1 adrenergic receptors in the liver plasma membranes of posthepatitic cirrhotic patients with portal hypertension were quantitatively measured using radioligand binding analysis.

RESULTS

Compared with 8 controls without hepatic pathological changes, the maximal binding capacity (Bmax) of 9 posthepatitic cirrhotic patients decreased (129.1 +/- 12.0 vs 142.1 +/- 14.1 fmol/mg protein, P > 0.05), dissociation constant (Kd) values increased (0.3945 +/- 0.0974 vs 0.2382 +/- 0.0548 nmol/L, P < 0.01), and the receptor maximal content (RMC) decreased (417.4 +/- 76.8 vs 739.9 +/- 167.6 fmol/g liver, P < 0.01).

CONCLUSIONS

The decreased concentration and affinity of alpha-1 adrenergic receptors may play an important role in the metabolic disturbances of catecholamines often seen in some cirrhotic patients, and have implications in the pathogenesis of portal hypertension.

Identification of a cyclin subunit required for the function of Drosophila P-TEFb

P-TEFb is required for the transition from abortive elongation into productive elongation and is capable of phosphorylating the carboxyl-terminal domain (CTD) of the largest subunit of RNA polymerase II. We cloned a cDNA encoding the large subunit of Drosophila P-TEFb and found the predicted protein contained a cyclin motif. We now name the large subunit cyclin T and the previously cloned small subunit (Zhu, Y. R., Peery, T., Peng, J. M., Ramanathan, Y., Marshall, N., Marshall, T., Amendt, B., Mathews, M. B., and Price, D. H. (1997) Genes Dev. 11, 2622-2632) cyclin-dependent kinase 9 (CDK9). Recombinant P-TEFb produced in baculovirus-transfected Sf9 cells exhibited 5, 6-dichloro-1-beta-D-ribofuranosylbenzimidazole-sensitive kinase activity similar to native P-TEFb. Kc cell nuclear extract depleted of P-TEFb failed to generate long DRB-sensitive transcripts, but this activity was restored upon addition of either native or recombinant P-TEFb. Like other CDKs, CDK9 is essentially inactive in the absence of its cyclin partner. P-TEFb containing a CDK9 mutation that knocked out the kinase activity did not function in transcription. Deletion of the carboxyl-terminal domain of cyclin T in P-TEFb reduced both the kinase and transcription activity to about 10%. The CDK-activating kinase in TFIIH was unable to activate the CTD kinase activity of P-TEFb.

[Magnetic resonance imaging of hypopharyngeal and cervical esophageal cancer]

Imaging by MR (MRI) and esophageal barium meal of 17 cases of hypopharyngeal and cervical esophageal cancer were analyzed. The results indicate that esophageal barium meal can not demonstrate the invading of neoplasms to the adjacent structure. Therefore, it is difficult to use the only data of esophageal barium meal for TNM staging. The results also indicate that MRI is more useful and reliable in assessing the three dimensional structure and the neoplasms invading to the adjacent structure. This results suggest that MRI is that useful in determining the diagnosis, TNM staging and the determining the appropriate operative therapy for hypopharyngeal and cervical esophageal cancer.

[Simultaneous determination of creatinine, pseudouridine and uric acid in serum and urine by high performance liquid chromatography]

In this paper a sensitive, rapid and simple HPLC method for the simultaneous determination of creatinine (Cr), pseudouridine (Pu) and uric acid(UA) has been established. We have evaluated clinical value of the method in the early diagnosis of diabetic nephropathy (DN). Separation was obtained using Shim-pack CLC-ODS 15 x 0.6 cm column and mobile phase of buffer solution of phosphate (pH 3.0, 0.02 mol/L) with flow rate of 1 mL/min. Detection was performed with UV detector at an automatic adjustment of wavelength. The recoveries of Cr, Pu and UA were 101.4%, 104.9% and 105.0% respectively. The calibration curves were linear within the concentration range of 8.6-274.6 mumol/L for Cr, 0.72-22.93 mumol/L for Pu and 19.1-612.7 mumol/L for UA (n = 6, r > 0.999, p < 0.01). The CV for within day and between day measurements were < 2.5% and < 5.0% respectively. In addition, Pu, Cr and UA were simultaneously determined in serum and urine of 39 patients with diabetic mellitus (DM). 15 patients with nephrotic syndrome (NS) and 53 normal subjects by the method. Results include: 1. the levels of serum Pu in all DM patients (100%) with microalbuminuria (MiAU) and macroalbuminuria (MaAU) were greater than maximum of normal subjects (X + 2S). In addition, in 9 DM patients (41%) with normal albuminuria (NAU) the levels were also greater than the maximum. 2. In patients with DM, there was no correlation between the serum Pu and the urinary albumin excretion (UAE), whereas the serum Pu correlated closely with the serum Cr. However, the incidence for serum Pu increase was significantly greater in patients. 3. The levels of serum Pu in patients with NS were greater than those in control subjects and patients with DM. Conclusion is that the determination of serum Pu could be used as sensitivity index for the early diagnosis of DN.

Identification of multiple cyclin subunits of human P-TEFb

The transition from abortive into productive elongation is proposed to be controlled by a positive transcription elongation factor b (P-TEFb) through phosphorylation of the carboxy-terminal domain (CTD) of the largest subunit of RNA polymerase II. Drosophila P-TEFb was identified recently as a cyclin-dependent kinase (CDK9) paired with a cyclin subunit (cyclin T). We demonstrate here the cloning of multiple cyclin subunits of human P-TEFb (T1 and T2). Cyclin T2 has two forms (T2a and T2b) because of alternative splicing. Both cyclin T1 and T2 are ubiquitously expressed. Immunoprecipitation and immunodepletion experiments carried out on HeLa nuclear extract (HNE) indicated that cyclin T1 and T2 were associated with CDK9 in a mutually exclusive manner and that almost all CDK9 was associated with either cyclin T1 or T2. Recombinant CDK9/cyclin T1, CDK9/cyclin T2a, and CDK9/cyclin T2b produced in Sf9 cells possessed DRB-sensitive kinase activity and functioned in transcription elongation in vitro. Either cyclin T1 or T2 was required to activate CDK9, and the truncation of the carboxyl terminus of the cyclin reduced, but did not eliminate, P-TEFb activity. Cotransfection experiments indicated that all three CDK9/cyclin combinations dramatically activated the CMV promoter.

The DFRC Method for Lignin Analysis. 4. Lignin Dimers Isolated from DFRC-Degraded Loblolly Pine Wood

Sixteen lignin dimers were directly isolated by gel permeation and reversed-phase TLC and HPLC from loblolly pine (Pinus taeda L.) sapwood following large-scale application of the new derivatization followed by reductive cleavage (DFRC) procedure. Their structures were elucidated by GC/MS and NMR. These dimers included representatives from all of the common interunit linkages in softwood lignins (beta-1, beta-beta, 5-5, beta-5, and 5-O-4). The DFRC procedure efficiently cleaves beta-aryl ethers, the major structural unit, so beta-ethers were not found among the dimeric products. All but two of the isolated dimers were guaiacyl-guaiacyl (from coniferyl alcohol-derived units in lignin); small amounts of p-hydroxyphenyl/guaiacyl beta-5 and beta-1 dimers were characterized. Several dimers have benzaldehydes as one unit-since aldehydes are not created by the procedure, they are either present in the native lignin or are formed during the minimal preparation of the wood. The dimers isolated and identified here will eventually allow their quantitation to aid in the structural analyses of wide-ranging plant materials.

[Purification and properties of antifungal protein X98III from Bacillus subtilis]

Bacillus subtilis BS-98 is one of the antagonistic strains strongly against plant fungal pathogens such as Physalospora piricola Nose. The antifungal protein was purified by ammonium sulphate precipitation and column chromatography on Sephadex G-100 and DEAE-cellulose, and it was named X98III. Molecular weight of X98III is 59,000 by SDS-PAGE and PI value is 4.50 by PAG-IEF, respectively. X98III was demonstrated as glycoprotein and lipoprotein by CAM (cellulose acetate membrane) electrophoresis and special staining. We estimated it contains 6% saccharides by using DNS methods. This protein was also found to be thermostabale and partially sensitive to proteinases. The amino acid analysis of the protein X98III showed that it comprises of 11 different amino acids and Glu, Tyr, Cys are the abundant amino acids. No Asp, Phe and Met were found. Purified X98III has strong inhibiting activity against the pathogens of Physalospora piricola, Phoma asparagi, etc. The antifungal mechanism of X98III was mainly disintegration of the cell wall to make the hyphae abnormal and the spores germinate abnormally or can not germinate at all.

The Arabidopsis GAI gene defines a signaling pathway that negatively regulates gibberellin responses

The Arabidopsis gai mutant allele confers a reduction in gibberellin (GA) responsiveness. Here we report the molecular cloning of GAI and a closely related gene GRS. The predicted GAI (wild-type) and gai (mutant) proteins differ only by the deletion of a 17-amino-acid segment from within the amino-terminal region. GAI and GRS contain nuclear localization signals, a region of homology to a putative transcription factor, and motifs characteristic of transcriptional coactivators. Genetic analysis indicates that GAI is a repressor of GA responses, that GA can release this repression, and that gai is a mutant repressor that is relatively resistant to the effects of GA. Mutations at SPY and GAR2 suppress the gai phenotype, indicating the involvement of GAI, SPY, and GAR2 in a signaling pathway that regulates GA responses negatively. The existence of this pathway suggests that GA modulates plant growth through derepression rather than through simple stimulation.

[Determination of Cu, Pb, Sn, Fe and Zn in the ancient Chinese bronzes by X-ray fluorescence filter paper method]

The determination of Cu, Pb, Sn, Fe and Zn in the ancient chinese bronzes has been performed using X-ray fluorescence filter paper method. The result is satisfactory. The samples are dissolved in the HCl-H2O2 system, ard then the solution is dropped on the filter paper. It is convenient for detection by XRF. In addition this method is efficient to reduce the matrix effect of sample. The correlative coefficients of calibration curves between element concentration and X-ray intensity are over 0.99. The rate of recovery is 97-104%, and the relative standard deviation for each element is less than 2.00%. The copper's result measured by this method agrees well with that of chemical method. This method is simple, rapid and accurate. It is also applied to determine the elements in the other ancient objects.

Erythropoietin administration increases production and reactivity of platelets in dogs

Administration of erythropoietin (EPO) to adult dogs resulted in a dramatic increase in the number of thiazole orange-positive (TO+) platelets, also referred to as reticulated platelets. Pre-treatment level of TO+ platelets was 6.2 +/- 0.5% (mean +/- 1 SE: n = 5); following day 5 of treatment with 500 U EPO/kg/day, the percentage of TO+ platelets peaked at 16.8 +/- 2.3% (n = 5; p <0.02). After cessation of the hormone, the number of TO+ platelets fell rapidly to below starting levels. Unexpectedly, there was a significant decline in total platelet count during EPO administration despite an increased level of TO+ platelets. To assess platelet reactivity, total platelets and TO+ platelets from EPO-treated dogs were analyzed for thrombin-responsiveness as quantitated by P-selectin expression on the cell surface; reactivity was expressed as a thrombin EC50, the thrombin concentration required to activate 50% of platelets. Both total and TO+ platelets were hyperreactive during EPO treatment when compared either to pre-treatment values or to control animals. Thrombin EC50 values for total and TO+ platelets on day 5 fell to 66.5 +/- 5.4% (mean +/- 1 SE; n = 5; p <0.02) and 62.2 +/- 8.7% (n = 5; p <0.025), respectively, of pre-treatment levels. These data indicate that EPO not only promotes the synthesis of increased numbers of TO+ platelets in the dog but that these newly produced platelets are hyperreactive when compared to TO+ platelets from control animals.

Transcription elongation factor P-TEFb is required for HIV-1 tat transactivation in vitro

P-TEFb is a key regulator of the process controlling the processivity of RNA polymerase II and possesses a kinase activity that can phosphorylate the carboxy-terminal domain of the largest subunit of RNA polymerase II. Here we report the cloning of the small subunit of Drosophila P-TEFb and the finding that it encodes a Cdc2-related protein kinase. Sequence comparison suggests that a protein with 72% identity, PITALRE, could be the human homolog of the Drosophila protein. Functional homology was suggested by transcriptional analysis of an RNA polymerase II promoter with HeLa nuclear extract depleted of PITALRE. Because the depleted extract lost the ability to produce long DRB-sensitive transcripts and this loss was reversed by the addition of purified Drosophila P-TEFb, we propose that PITALRE is a component of human P-TEFb. In addition, we found that PITALRE associated with the activation domain of HIV-1 Tat, indicating that P-TEFb is a Tat-associated kinase (TAK). An in vitro transcription assay demonstrates that the effect of Tat on transcription elongation requires P-TEFb and suggests that the enhancement of transcriptional processivity by Tat is attributable to enhanced function of P-TEFb on the HIV-1 LTR.

P-TEFb kinase is required for HIV Tat transcriptional activation in vivo and in vitro

To identify novel inhibitors of transcriptional activation by the HIV Tat protein, we used a combination of in vitro and in vivo Tat-dependent transcription assays to screen >100,000 compounds. All compounds identified blocked Tat-dependent stimulation of transcriptional elongation. Analysis of a panel of structurally diverse inhibitors indicated that their target is the human homolog of Drosophila positive transcription elongation factor b (P-TEFb). Loss of Tat transactivation in extracts depleted of the kinase subunit of human P-TEFb, PITALRE, was reversed by addition of partially purified human P-TEFb. Transfection experiments with wild-type or kinase knockout PITALRE demonstrated that P-TEFb is required for Tat function. Our results suggest that P-TEFb represents an attractive target for the development of novel HIV therapeutics.

[Significance of p16 and C-myc expression in the laryngeal squamous cell carcinoma]

OBJECTIVE

To study the clinical significance of p16 and C-myc expression in the laryngeal squamous cell carcinoma (LSCC).

METHOD

Immunohisto-chemical detection of p16 proteins and C-myc proteins, in 47 cases of LSCC and 6 cases of normal tissues from the larynx, were conducted in paraffin-embeded sections.

RESULTS

No staining was found in 6 cases of normal tissue; The positive expression of p16 and C-myc proteins expression rates did not correlate with sex, age and position of the tumors (P > 0.05); but related to the staging and grade of LSCC (P < 0.05). The expression of C-myc proteins were higher in the case with lymph nodal metastasis than that without lymph nodal metastasis (P < 0.05).

CONCLUSION

The expression of p16 and C-myc protein may play an important role in the development of LSCC, and may be a new indicator to assess the prognosis of LSCC.

Polychlorinated biphenyl congener 153-induced ultrastructural alterations in rat liver: a quantitative study

Alterations in the liver of male and female Sprague-Dawley rats fed PCB congener 153 (2,2',4,4',5,5'-hexachlorobiphenyl) at 0.5, 5, or 50 ppm concentrations in diets for 13 weeks were determined morphometrically. A dose-dependent increase in hepatocyte volume was detected; the cytoplasmic compartment contributed to the increase in cell volume in an overwhelming fashion. Eighty percent and 250% increase in smooth endoplasmic reticulum volume and its surface area in hepatocytes were estimated in animals of both genders from 5- and 50-ppm groups, respectively; the organelle played the largest part in the increase in cytoplasmic volume. Rough endoplasmic reticulum alteration was shown to depend on gender, where the volume per hepatocyte was augmented by 40% and 45% in females of 5- and 50-ppm groups, respectively, however, 30% and 20% decreases in volume of this organelle were noted in males at those congener concentrations. A decrease of 13% in normal mitochondria volume at 50 ppm concentration was observed, which may have been a consequence of a transformation of these mitochondria to abnormal types. Two types of abnormal mitochondria, named Type I and Type II, were defined: the former comprised mitochondria that had cristae which laying parallel to the long axis of the organelle and the latter showed C- or ring-shaped profiles. Data analysis revealed a trend toward an increase in abnormal mitochondria volume in the cells as the congener concentration elevated. In addition, a threefold increase in the volume of lysosomal elements per hepatocyte was noted in 50 ppm PCB-fed rats of both genders. Also, a significant increase in peroxisome volume per cell in female rats was detected at a lower concentration than it was in the male. This study, which is a first ultrastructural quantitative investigation on the effects of a PCB that included many parameters. The methodology, and the data may prove useful to provide better understanding of pathology in the evaluation and regulation of toxic chemicals.

Gibberellin deficiency and response mutations suppress the stem elongation phenotype of phytochrome-deficient mutants of Arabidopsis

Plant growth and development are regulated by numerous internal and external factors. Among these, gibberellin (GA) (an endogenous plant growth regulator) and phytochrome (a photoreceptor) often influence the same processes. For example, in plants grown in the light Arabidopsis thaliana hypocotyl elongation is reduced by GA deficiency and increased by phytochrome deficiency. Here we describe experiments in which the phenotypes of Arabidopsis plants doubly homozygous for GA-related and phytochrome-related mutations were examined. The double mutants were studied at various stages in the plant life cycle, including the seed germination, young seedling, adult, and reproductive phases of development. The results of these experiments are complex, but indicate that a fully functional GA system is necessary for full expression of the elongated phenotypes conferred by phytochrome deficiency.

Activation of AP-1 by okadaic acid in mouse keratinocytes associated with hyperphosphorylation of c-jun

Okadaic acid (OA), a specific inhibitor of protein phosphatases 1 and 2A, is also a potent mouse skin tumor promoter. The effects of OA on regulation of c-jun/activator protein-1 (AP-1) transcriptional activation were investigated in mouse keratinocytes. AP-1 DNA binding to the jun 12-O-tetradecanoylphorbol-13-acetate-response element (TGACATCA) as determined by gel shift analysis was strongly induced by OA (100 ng/mL) at 6 and 12 h. Preincubation of nuclear extracts with anti-c-jun antibody demonstrated that c-jun was a major component of the DNA-bound AP-1 complex induced by OA in 308 cells. Transfection of a c-jun promoter-reporter construct demonstrated that AP-1 transactivation was induced by OA. The mRNA level of the c-jun proto-oncogene was dramatically increased by 6 and 12 h of OA treatment. Furthermore, a significant induction of c-jun protein was stimulated by 6 and 12 h of OA treatment. Upon further analysis, it was found that OA induced a significant accumulation of Ser 73-phosphorylated c-jun protein in 308 cells. In summary, our data suggest that skin tumor promotion by OA is due at least in part to increased AP-1 DNA binding and transactivation mediated by c-jun hyperphosphorylation.