BCL2 and cancer: Inhibition of these BCL-2 family proteins with small molecules has been extensively investigated as a therapeutic strategy for cancers, resulting in the discovery of ABT263 (navitoclax, a BCL-2 and BCL-XL dual inhibitor), ABT199 (venetoclax, a BCL-2 selective inhibitor), and several BCL-XL and MCL-1 monoselective inhibitors as promising anticancer drug candidates.