ABCB1 and hepatocellular carcinoma: Liang et al. also showed that catechins inhibit the expression of multidrug resistance 1 (MDR1) mRNA and decrease the levels of P-glycoprotein, a membrane transporter that pumps a wide range of xenobiotics [41], in DOX-resistant HCC cells, suggesting that the administration of DOX in combination with EGCG or epicatechin gallate inhibits P-glycoprotein efflux pump activity and markedly enhances intracellular DOX accumulation [40].