Canalicular multispecific organic anion transporter 1 (ABCC2 aka multidrug resistance-associated protein 2, MRP2), in addition to transporting many organic anions, mediates the ATP-dependent transport of glutathione and glucuronate conjugates from hepatocytes into bile. ABCC2 transports with high affinity and efficiency mono- and di-glucuronated bilirubin into bile. Bilirubin, the end product of heme breakdown, is an important constituent of bile and is responsible for its characteristic colour. Defects in ABCC2 can cause Dubin-Johnson syndrome (DJS; MIM:237500), an autosomal recessive disorder characterised by conjugated hyperbilirubinemia. Mutations causing DJS include I1173F, R1150H, R768W and R1066* (Mar-Cohen et al. 2001, Wada et al. 1998, Pacifico et al. 2010).