ABCB4 and sclerosing cholangitis: In the Mdr2 KO (Abcb4 KO) model of cholestatic liver injury and sclerosing cholangitis, pharmacological inhibition of the ileal BA transporter (IBAT/ASBT; Slc10a2) increases fecal BA elimination, leading to reductions in liver BA concentrations and improvement in biomarkers of hepatocellular and cholestatic damage (8, 19).