Insulin Activates a p21-activated Kinase in Muscle Cells via Phosphatidylinositol 3-Kinase*

Insulin activates rapidly a complex cascade of lipid and protein kinases leading to stimulation of mitogenic and metabolic events. Here we describe a renaturable kinase of 65 kDa (PK65) that becomes rapidly activated by insulin in differentiated L6 muscle cells (myotubes) and can phosphorylate histones immobilized in polyacrylamide gels. Insulin activation of PK65 was abolished by the tyrosine kinase inhibitor erbstatin and by the …