Potent cyclin-dependent kinase 4 (cdk4) and cdk6 inhibitor (IC50 values are 11 nM and 15 nM respectively). Also displays activity at cdk2, cdk5 and cdk9 (IC50 values reported to be 1.6, 1.8 and 0.42-1.1 μM, respectively). Induces G1 cell cycle arrest and senescence in retinoblastoma protein (Rb)-proficient cell lines; blocks growth of intracranial glioblastoma multiforme xenografts in mice. Brain penetrant. Purity 98%. MW (observed): 573.66