MCL1 and breast cancer: MCL-1 is a compelling cancer target in its own right, having been implicated in mediating the survival of multiple tumor types.23 The MCL1 gene locus is amplified in a variety of tumor types, including breast cancer and non-small cell lung cancer (NSCLC),24 and the MCL-1 protein has been shown to mediate survival in models of multiple myeloma,25, 26 acute myeloid leukemia27 and NSCLC28, 29 and MYC-driven lymphomas.30