To test this hypothesis, we assessed the recruitment of the proapoptotic protein Bim to Mcl-1, Bcl-xL, and Bcl-2 following incubation with BH domain antagonists (VEN, S63845, or A1155463) in agonist mix–treated primary CLL cells that exhibited overexpression of antiapoptotic proteins and multidrug resistance. The gene discussed is MCL1; the disease is B-cell chronic lymphocytic leukemia.