Indeed, previous studies have shown that upregulated expression of Mrp4 at the basolateral membrane seems to be responsible for the high circulating BA levels during a cholestatic injury in rodents and pediatric patients with progressive familial intrahepatic cholestasis (Keitel et al., 2005; Miura et al., 2011). This evidence concerns the gene ABCC4 and familial intrahepatic cholestasis.