MCL1 and B-cell chronic lymphocytic leukemia: Furthermore, given the described compensatory upregulation of other anti-apoptotic BCL-2 family members such as MCL-1 and BFL-1/A1 in response to ABT-737 treatment in lymphoma [123] and BCL-xL in response to venetoclax in CLL, identification of these changes via BH3 profiling may allow for sequential use of novel inhibitors such as those against MCL-1 or BCL-xL to combat acquired resistance.