Purvalanol B inhibits cyclin-dependent kinases with IC50 values of 6, 6, 9, > 10,000, and 6 nM for cdc2/cyclin B, cdk2/cyclin A, cdk2/cyclin E, cdk4/cyclin D1 and cdk5-p35 respectively. Has also been shown to have anti-proliferative properties, mediated