A CDK/CRK-specific kinase inhibitor (IC50s = 9-839 nM, in vitro); selective, exhibiting less than 20% inhibition of 60 non-CDK/CRK kinases, at a concentration of 1 μM; induces cell cycle arrest in the G1 phase, endoreduplication, and apoptosis in HCT116 cells; exhibits broad anti-tumor activity with an average GI50 value of 50 = 40 nM)