MCL-1 inhibition sensitizes hepatoma cells to the BCL-xL inhibitor A-1331852. (A) Representative Western blot images of MCL-1, BCL-xL, BIM, BCL-2, BAX, BAK, and β-Actin exhibited by Hep3B and HepG2 cells at different times (0–16 h) after regorafenib treatment (5 µM). (B) Effect of the MCL-1 inhibitor A-1210477 on Hep3B cells and HepG2 cells treated with A-1331852 (A, 0.05, 0.1, or 0.2 µM) for 24 h. * p < 0.05 vs. control cells. (C) Hep3B spheroids were seeded and after 24 h of aggregation treated with vehicle, regorafenib (R, 2.5 μM), and/or A-1331852 (A, 0.1 or 0.2 µM) for seven days. Spheroid growth was monitored daily (scale bar, 500 µm). (n = 3) * p < 0.05 vs. control cells, # p < 0.05 vs. regorafenib-treated cells.