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. This evidence concerns the gene BCL2 and B-cell chronic lymphocytic leukemia.