AtRA supplementation with UDCA synergistically repressed Cyp7a1 mRNA expression in vivo in BDL rat livers (A) and great repression of CYP7A1 expression in vitro in human hepatocytes by atRA +/− UDCA (B), where increased mRNA expression of SHP/Shp and FGF19/Fgf15 were also detected. For A, p < 0.05, n=5–7, * to sham, † to BDL-PBS, # to BDL-UDCA, and & to BDL-atRA. Both = BDL-UDCA&atRA.