MCL1 and acute myeloid leukemia: They also raise a potential mechanism for the interaction between CS055 and ABT-199, in which while CS055 induces Bim expression, inhibition of Bcl-2 by ABT-199 and downregulation of Mcl-1 and Bcl-xL by CS055 could fully unleash and activate Bim to induce apoptosis and probably to overcome ABT-199 resistance in AML cells (Fig. 8).