Liu G, Takano T, Amino N. TGF-beta 1 inhibits the cell proliferation stimulated by IGF-I by blocking the tyrosine phosphorylation of 175kDa substrate.
Endocr Res 1996;
22:277-87. [PMID:
8875139 DOI:
10.3109/07435809609030512]
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Abstract
TGF-beta strongly inhibits the mitogenic effect of growth factors such as insulin-like growth-I (IGF-I) on thyroid follicular cells. To study the mechanism of this inhibiting action, the effect of TGF-beta 1 on tyrosine phosphorylation of 175kDa substrate induced by IGF-I was investigated in FRTL-5 thyroid epithelial cells. After treatment with TGF-beta 1, tyrosine phosphorylation of 175kDa protein induced by IGF-I was inhibited in parallel with the degree of the inhibition of cell proliferation. However, TGF-beta 1 had no effect on tyrosine phosphorylation of 120kDa substrate. These results suggest that TGF-beta 1 blocks the mitogenic signal of IGF-I by inhibiting the tyrosine phosphorylation of 175kDa substrate in FRTL-5 cells.
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