There has been intense activity to develop BH3-mimetics to target MCL-1 with recent progress; A1210477 shows impressive anti-cancer effects in vitro on diverse cancer cell lines13,14; UMI-77 is effective as a single agent on pancreatic cancer cell lines in vitro and in xenograft models15; and S63845 shows tumour-specific cell killing in leukaemia, lymphoma and myeloma in a variety of in vitro, xenograft and genetically modified mouse models16. This evidence concerns the gene MCL1 and cancer.