BCL-XL and MCL1 are the major pro-survival proteins in solid tumours (Cancer Cell Line Encyclopaedia (CCLE; https://portals.broadinstitute.org/ccle) and The Cancer Genome Atlas (TCGA; https://cancergenome.nih.gov/)), but development of MCL1 inhibitors (MCL1i) has lagged behind that of BCL2/BCL-w/BCL-XL inhibitors due to challenges associated with targeting the MCL1 BH3-binding groove8,29,30. Here, MCL1 is linked to cancer.