Regorafenib-resistant HepG2 cells, exhibiting mRNA changes in BCL-xL and MCL-1, are re-sensitized to regorafenib by A-1331582. (A) Representative Western blot images of MCL-1, BCL-xL, BCL-2, BIM, and β-Actin protein levels in S and R HepG2 cells. * p < 0.05 vs. sensitive cells. (B) Effect of A-1331852 (A, 0.01 or 0.1 µM) on S and R HepG2 cells. * p < 0.05 vs. control cells. (C) Subcutaneous growth of R HepG2 cells in mice treated orally with A-1331852 (25 mg/kg) and regorafenib (30 mg/kg) for 2 weeks (n = 4). (D) Representative images of PCNA expression in tumors from HepG2 R CDXs (scale bar, 100 µm). * p < 0.05 vs. vehicle-treated mice.