Although the expression levels of Na/Taurocholate Cotransporting Polypeptide (NTCP), a major transporter of hepatic BA (33), and FXR, a transcriptional regulator of BA synthesis and transport (34, 35), were not significantly different between the WT and CF rabbit livers, the expression levels of the transcripts encoding Cytochrome P450 Family 7 Subfamily A Member 1 (CYP7A1), the rate-limiting enzyme mediating BA biosynthesis and metabolism (36), in the CF rabbit livers was significantly reduced, compared to that of the WT rabbit livers (Fig. 2E). The gene discussed is SLC10A1; the disease is cystic fibrosis.