To further test the requirement for canonical MCL-1 function in human breast cancer stem cells we therefore used CRISPR/Cas9 editing to generate MCL1-, BAX/BAK- and MCL1/BAX/BAK-deficient versions of the human breast adenocarcinoma MDA-MB-231 cell line (Supplementary Fig. 5B). The gene discussed is BAX; the disease is breast cancer.