In contrast, IV administration of phytosterols provides large loads requiring excretion via biliary sterol transporters ATP-binding cassette subfamily G member 5/8 (ABCG5/G8; sterolin) located on the canalicular membrane, or export into the intestinal lumen by intestinal epithelia.28Impaired biliary excretion, such as in cholestasis and downregulation ofABCG5/G8, results in markedly elevated hepatic and circulating concentrations of phytosterols. The gene discussed is ABCG5; the disease is cholestasis.