20: Biochem Biophys Res Commun. 1996 Jul 5;224(1):180-3.
K252a inhibits the phosphorylation of pRb without changing the levels of G1
cyclins and Cdk2 protein in human hepatoma cells.
Nakayama T, Hashimoto Y, Kaneko Y, Kurokawa K.
First Department of Medicine, Faculty of Medicine, University of Tokyo, Japan.
A protein kinase inhibitor K252a suppressed the growth of HuH7 hepatoma cells
and the hyperphosphorylation of retinoblastoma protein (pRb) at late G1 phase of
cell cycle. However, K252a treatment did not alter the levels of cyclin D1,
cyclin E, cyclin A and Cdk2 protein bound to cyclin E or cyclin A. Therefore,
the K252a inhibition of pRb phosphorylation is considered to be brought about
probably by inhibiting the action of Cdk-cyclin complex rather than by changing
its cellular level. These results also suggest that K252a is a useful tool for
investigating the mechanism of phosphorylation of pRb mediated by Cdk-cyclin.
