CYP7A1 and cholestasis: Furthermore, expression of genes with importance for bile acid synthesis [e.g., CYP7A1, which catalyzes the rate-limiting step in the classic bile acid synthesis pathway] and bile transport [e.g., the canalicular transporter BSEP (encoded by ABCB11) and the sinusoidal transporters NTCP (SLC10A1) and OCT1 (SLC22A1)] were strongly downregulated, mirroring expression alterations seen in patients with cholestasis in vivo (Zollner et al., 2001, 2007; Chen et al., 2008; Nies et al., 2009).