MCL1 and cancer: Levels of BCL-2 are also generally decreased following BETi treatment [290,292,293,294,298,305], though notably, other pro-survival proteins including BCL-XL [292,298], MCL-1 [292] and BFL-1 [295] have been shown to be reduced in different cancer types, leading to a further reduction in the apoptotic threshold of the cell.