Bcl-xS has been shown to induce apoptosis in different cancer cell lines.18, 19, 20 Congruent with these studies, ectopic expression of Bcl-xS (Supplementary Figure S5A) caused release of cytochrome c from mitochondria to cytosol (Figure 5c), similar to what was seen in BC200 KO cells. Here, BCL2L1 is linked to cancer.