MCL1 and cancer: ABT-263, an orally available, selective inhibitor of the anti-apoptotic BCL-2 family proteins, including Bcl-2, Bcl-XL, and Mcl-1, has been demonstrated to possess antitumor activity against various types of cancers and is in clinical trials (Lever and Fergason-Cantrell, 2019; Ohgino et al., 2020).