PERSISTENT ACTIVATION OF CDK4 DURING NEURONAL DIFFERENTIATION OF RAT PHEOCHROMOCYTOMA PC12 CELLS

It has been shown that suppression of cyclin-dependent kinase 4 (CDK4) expression or its kinase activity is a critical event for the differe ntiation of hematopoietic and myoblastic cells. To investigate the rol e of CDK4 during NGF-mediated neuronal differentiation of PC12 cells, we examined the changes in the expression and kinase activity of CDK4, Unexpectedly, both the expression of CDK4 and its kinase activity rem ained high throughout 10 days of exposure to NGF. Furthermore, constit utive overexpression of the human CDK4 did not inhibit the differentia tion. These results suggest that suppression of CDK4 is not required f or the NGF-induced neuronal differentiation of PC12 cells. (C) 1996 Ac ademic Press, Inc.