RB1 and cancer: Furthermore, CDK2 has been reported to phosphorylate the p27KIP1 and RB proteins in cell cycle progression, the replication factors A and C in DNA replication, the NPAT in histone synthesis, and the nucleophosmin (NPM) in centrosome duplication (Meraldi et al. 1999).Taken together these studies strongly suggested an important role of CDK2 in human HCC, and a CDK2/4/6 triple inhibitor, vanoxerine dihydrochloride, may have additional advantages and broader anti-cancer activities than CDK4/6 dual inhibitors for the treatment of human HCC.