BCL-XL belongs to key mediators of sensitivity/resistance to VEN-induced apoptosis. (A) Representative western blot analysis confirms absence of BCL-XL protein expression in the HBL-2 and MAVER-1 lymphoma clones with K/O of BCL-XL gene. (B) Calculated lethal dose 50 (LD₅₀) for A1155463 and VEN in the HBL-2 and MAVER-1 cell clones with BCL-XL K/O compared with the WT lymphoma cell lines. (C) Western blot analysis confirms doxycycline-induced dose-dependent re-expression of BCL-XL protein in HBL-2 BCL-XL K/O clone with transgenic re-expression of BCL-XL (designated BCL-XL K/O R); expression of BCL-XL in the WT HBL-2 cell line is shown for comparison. (D) Extent of the doxycycline-induced transgenic re-expression of BCL-XL in the HBL-2 BCL-XL K/O R clone under doxycycline promotor negatively correlates with sensitivity to VEN; sensitivity to HBL-2 WT cell line and HBL-2 BCL-XL K/O clone is shown for comparison. DOX, doxycycline.