MCL1 and cancer: Based on the fact that pro‐survival BCL‐2 proteins are frequently linked with cancer progression and chemotherapy resistance, a number of highly specific BH3‐mimetic compounds have been developed, including pan‐BCL‐2‐targeting ABT‐737/ABT‐263 (Oltersdorf et al, 2005; van Delft et al, 2006; Tse et al, 2008), MCL‐1‐targeting S63845 (Kotschy et al, 2016), and BCL‐2‐targeting ABT‐199 (Souers et al, 2013).