A similar ribosomal protein S6 kinase activity is found in insulin-treated 3T3-L1 cells and chick embryo fibroblasts transformed by Rous sarcoma virus

Insulin and transformation by Rous sarcoma virus stimulate the phosphorylation of ribosomal protein S6. Soluble fractions containing activated S6 protein kinase from insulin-treated cells and from transformed chick embryo fibroblasts were compared. Based upon several characteristics notably elution from DEAE-cellulose and sedimentation in glycerol gradients, these two S6 protein kinase activities appear to be similar enzymes. Thus insulin and retroviral transformation may activate the same enzyme to regulate the phosphorylation state of S6.