MRP2 (Canalicular multispecific organic anion transporter 1) mediates hepatobiliary e, Xenopus/Amphibian,cretion of numerous organic anions. MRP2 is found on the apical membrane of polarized cells in the liver, kidney, intestine, with the highest e, Xenopus/Amphibian,pression in liver. Defects in MRP2 are the cause of Dubin-Johnson syndrome (DJS), an autosomal recessive disorder characterized by conjugated hyperbilirubinemia, an increase in the urinary e, Xenopus/Amphibian,cretion of coproporphyrin isomer I, deposition of melanin-like pigment in hepatocytes, and prolonged retention of sulfobromophthalein, but otherwise normal liver function.