Cyclin-dependent kinase (cdk) 4 inhibitor (IC50 = 6.0 μM at cdk4/cyclin D1) that displays > 33-fold selectivity over cdk2 (IC50 > 200 μM at cdk2/cyclin A). Cytotoxic against a range of human cancer cells (IC50 values are 0.30, 0.61, 1.08 and 1.21 μg/mL for HL-60, A549, Col 1 and HepG2 cells respectively).