Protein tyrosine kinases couple the interleukin‐2 receptor to p21^ras

The T cell growth factor interleukin‐2 (IL‐2) induces p21^ras activation in T lymphocytes. We have previously shown that a protein kinase C (PKC)‐mediated pathway for p21^ras regulation exists in T cells and that the IL‐2 receptor (IL‐2R) can couple to p21^ras independently of the presence of the PKC pathway for p21^ras 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 p21^ras was blocked. Herbimycin did not inhibit the PKC‐mediated pathway for p21^ras regulation. Thus, the data indicate that PTK are involved in the coupling of the IL‐2R to p21^ras.