MCL1 and leukemia: Irrespective of the expression of anti-apoptotic BCL-2 family members, the re-programmed p185+ B-ALL cells in which endogenous MCL-1 was replaced by human BCL-2, BCL-XL, BCL-W, MCL-1, or BFL-1 all succumbed to a fatal leukemia with a similar kinetic (Figure 4A).