BCL2L1 and B-cell chronic lymphocytic leukemia: A variety of small molecules targeting anti-apoptotic proteins (BH3 mimetics) have been designed and tested in clinical trials.21, 22 ABT-199 (venetoclax), a Bcl-2-specific inhibitor, has recently been approved by the FDA for treatment of a CLL subtype.23 Another BH3 mimetic, ABT-737, was identified by library screening for high-affinity binding of recombinant Bcl-xL.