Curcumin and its major metabolite, namely tetrahydrocurcumin, have also been reported to down-regulate the expression and/or activity of multiple ABC multidrug transporters, including ABCG2, multidrug resistance 1 (MDR-1) encoding P-glycoprotein (ABCB1) and multidrug resistance protein-1 (MRP-1; ABCC1) in parental cancer cell lines and their derivatives that are resistant to multiple drugs, the SP cell fraction and patient leukemic cells in vitro and in mice in vivo [61-68]. Here, ABCB6 is linked to cancer.