Tyrosine protein phosphorylation is required for protein kinase C‐mediated proliferation in T cells

Abstract
We have studied the role of tyrosine kinase in PMA‐stimulated T cells. Protein kinase C (PKC)‐mediated D10A cell proliferation is inhibited by the specific inhibitor of tyrosine kinase, tyrphostin. This inhibitor selectively blocks the mRNA expression of the proto‐oncogene e‐mye in response to the phorbol ester. On the other hand, the same doses of this inhibitor do not affect the mRNA expression of the proto‐oncogene c‐for in PMA‐stimulated D10A cells. Phorbol esters induce in this T cell line the tyrosine phosphorylation of a unique protein of 42 kDa and the enzyme PKC is required for this activity.