Based on previous reports indicating that some of the ABC transporters may be responsible for the defect in Pt-drug accumulation in resistant cells [8–10] as well as a recent study documenting that cotreatment with emodin could remarkably enhance chemosensitivity of platinum-resistant gallbladder cancer cells to platinum drugs via ROS-related mechanisms and downregulation of MRP1 [14], we examined whether the emodin-enhanced cytotoxic effect of cDDP in COC1/DDP cells was correlated with expression of multidrug resistance-related protein 1 (MRP1). The gene discussed is ABCG2; the disease is gallbladder cancer.