ABCB1 and hepatocellular carcinoma: Bruceine D and silymarin are two newly discovered natural products that reverse drug resistance by decreasing HIF-1α expression and can directly block the inhibitor of B-catenin and T-cell factor/B-catenin interaction to regulate HCC cell metabolism, and silymarin reduces the expression of MDR1 and P-glycoprotein (191, 192).