MCL1 and B-cell chronic lymphocytic leukemia: In these experiments, the stimulation of CD40 sensitized CLL cells to anti‐CD20 therapy and increased the expression of anti‐apoptotic members of the Bcl‐2 family proteins (e.g., Bcl‐xl, Mcl‐1),43 rendering CLL cells resistant to conventional chemotherapy44 or therapy with the Bcl‐2 inhibitor venetoclax45 (Figure 2).