Protein tyrosine kinases couple the interleukin-2 receptor to p21ras

The T cell growth factor interleukin-2 (IL-2) induces p21ras activation in T lymphocytes. We have previously shown that a protein kinase C (PKC)-mediated pathway for p21ras regulation exists in T cells and that the IL-2 receptor (IL-2R) can couple to p21ras independently of the presence of the PKC pathway for p21ras regulation. Our data show that in conditions where cellular protein tyrosine kinases (PTK) were efficiently down-regulated by pretreatment with the specific PTK inhibitor herbimycin, the IL-2-induced activation of p21ras was blocked. Herbimycin did not inhibit the PKC-mediated pathway for p21ras regulation. Thus, the data indicate that PTK are involved in the coupling of the IL-2R to p21ras.