MCL1 and B-cell chronic lymphocytic leukemia: The pro-survival Bcl-2 proteins, including Bcl-2 and Mcl-1, are highly expressed in various cancers, including follicular lymphoma and chronic lymphocytic leukemia (CLL), and expression levels of multiple pro-survival Bcl-2 proteins, including Bcl-2 and Mcl-1, are correlated with survival outcomes, and resistance to chemotherapeutic agents [65].