AbstractThe 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.