Inhibitor of checkpoint kinase 1 (Chk1) that displays selectivity over other protein kinases (IC50 values are 15, 250 and 1000 nM for Chk1, cdc2 and PKC respectively). Abrogates G2 cell cycle arrest caused by γ-irradiation and topoisomerase I inhibition. Potentiates cytotoxicity of DNA-damaging drugs, enhancing the efficacy of some chemotherapeutics.