Emodin was also reported as a strong inhibitor of P-glycoprotein in the MDR1-transfected Madin–Darby Canine Kidney II (MDR1-MDCK II) and Caco-2 cells (IC50=9.42 μM) [29], and inhibited the expression of the ATP-binding cassette super-family G member (ABCG2) in gallbladder carcinoma [30]. This evidence concerns the gene ABCG2 and gallbladder carcinoma.