CHEK1 and acute myeloid leukemia: We have previously demonstrated that DNA damaging agents daunorubicin, cytarabine, and CHK1-selective inhibitor LY2603618 downregulate Mcl-1 and enhance ABT-199-induced apoptosis in AML cells.11,30 It has been reported that dual PI3K/mTOR inhibitor, NVP-BEZ235, downregulates Mcl-1 and sensitizes leukemic cells to ABT-199.35 Inhibition of CDK9 has also been shown to enhance ABT-199 sensitivity through downregulation of Mcl-1.36 In summary, the Mcl-1 inhibitor A-1210477 enhances ABT-199-induced apoptosis in AML cells, though synergistic results were also revealed in normal PMNCs.