Roscovitine is a purine analog that competes with ATP for a binding site on cyclin-dependent kinases (CDKs) (Figure 1).46 This small molecule inhibits CDK-induced apoptosis in isolated CLL cells by caspase activation and modulation of Bcl-2 family proteins.46 Roscovitine and its pure R-enantiomer CYC202 (R-Roscovitine, Seliciclib) are independent of p53 activation or defects in p-53 dependent pathways. The gene discussed is TP53; the disease is B-cell chronic lymphocytic leukemia.