BCL2 and B-cell chronic lymphocytic leukemia: We transfected MEC1 versus MEC1-ROR1 cells with GFP-tagged plasmids encoding either wild type (WT) BCL2 (BCL2WT) or one of the mutant BCL2 identified in the CLL cells of patients resistant to venetoclax and assessed the capacity of each to enhance the resistance of these cells to treatment with venetoclax in vitro.