To validate the efficacy of BH3 profiling on cells addicted to specific BCL-2 family members, primary CLL cells, addicted to BCL-2 (Del Gaizo Moore et al, 2007; Vogler et al, 2009a, 2009b), MOLT-4 and H929 cell lines, addicted to BCL-XL (Leverson et al, 2015a) and MCL-1 (Leverson et al, 2015b), respectively, and H1299 cells addicted to both BCL-XL and MCL-1 (Varadarajan et al, 2013) were selected. Here, MCL1 is linked to B-cell chronic lymphocytic leukemia.