ABCB1 and cholestasis: Although these are minor pathways under normal physiological conditions, hepatic phase I/II metabolism of BAs is induced as an adaptive response to cholestasis.11 If canalicular secretion is intact, polyhydroxylated BAs are secreted into bile by the multidrug resistance-associated protein-2 (MRP2; ABCC2), P-glycoprotein (MDR1; ABCB1), and BSEP,12 whereas sulfated and glucuronidated BAs are secreted into bile primarily by MRP2.