CDK5 and neoplasm: Dinaciclib, a multi-target Cdk1, Cdk2, Cdk5 and Cdk9 second-generation inhibitor, leads to the arrest of cell-cycle progression and induces apoptosis in various tumor cells.4,7In vivo studies indicate that dinaciclib indeed has anti-tumor effects and reduces tumor growth.4,8 Saqub et al. already showed that dinaciclib is able to prevent proliferation of tumor cells in vitro and in vivo.