Apoptosis induced by this agent was preceded by the release of Bak from Mcl-1, liberation of Bim from both Bcl-2 and Mcl-1 and the formation of an active Bak/Bax complex.38 O’Brien et al.40 reported the results of a phase I trial of obatoclax in CLL patients. This evidence concerns the gene MCL1 and B-cell chronic lymphocytic leukemia.