Abstract
ABSTRACT: Tyrosine kinases are important in the signal transduc-tion of a number of growth factors. As shown previously, transforming growth factor (TGF)-α stimulated proliferation of type II cells in vitro. The mitogenic effect of TGF-α could be blocked by the addition of the tyrosine kinase inhibitors genistein or tyrphostin. Tyrosine phosphorylation in type II cells exposed to growth factors was examined using an antiphosphotyrosine antibody. After addition of TGF-α, phosphorylation of a tyrosine protein with a molecular mass of 170 kD, presumed to be the epidermal growth factor receptor (EGF-R), peaked by 5 min, returning to baseline by 30 min. As expected, genistein or tyrphostin decreased the TGF-α -induced phosphorylation of the EGF-R. Addition of TGF-β resulted in no newly phosphorylated tyrosine proteins. TGF-β decreased the TGF-α -induced phosphorylation of the EGF-R. Previous work has shown that TGF-β blocks the TGF-α stimulation of type II cell proliferation. It appears that TGF-β interferes with TGF-α -induced phosphorylation of the EGF-R.
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Chess, P., Ryan, R. & Finkelstein, J. Tyrosine Kinase Activity Is Necessary for Growth Factor-Stimulated Rabbit Type II Pneumocyte Proliferation. Pediatr Res 36, 481–486 (1994). https://doi.org/10.1203/00006450-199410000-00012
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DOI: https://doi.org/10.1203/00006450-199410000-00012
