ABCG2 and hepatocellular carcinoma: Having shown the increased expression of MDR1 and ABCG2 on the EpCAM+–CD133+ subpopulation of the HCC cells and confirmed their capacity to extrude the respective substrates calcein-AM and Hoechst 33342 (Supplementary Fig. S1), we proceeded to determine if the increased expression of MDR1 and ABCG2 in the EpCAM+–CD133+ LCSCs is associated with the reduction in cellular DOX accumulation.