BCL2 and chronic myelogenous leukemia, BCR-ABL1 positive: Using BH3 profiling, a peptide-based technique to determine BCL-2 family dependencies,25 we observed extensive loss of mitochondrial membrane potential (φm) in two CML cell lines, K562 and KCL22, following exposure to increasing concentrations of different BH3 peptides (Figure 1a and Supplementary Figure S1).