A cell-permeable pyrrolo-pyrazine compound that acts as a potent, selective, reversible, and ATP-competitive inhibitor of cyclin dependent kinases (Cdks: IC50 =150nM, 120 nM, 400 nM and 200 nM for Cdk1/cyclin B, Cdk2/cyclin A, Cdk2/cyclin E, and Cdk5/p25, |