In chronic lymphocytic leukemia (CLL) the cellular responses to the dual CDC7-CDK9 inhibitor PHA-767491 have been studied in some detail and it was observed that these can be greatly influenced by the activation of signaling pathways that confer microenvironmental drug resistance leading to either apoptosis or proliferation arrest [26]. The gene discussed is CDC7; the disease is B-cell chronic lymphocytic leukemia.