Thus, biopsies of PSC patients with mild cholestatic liver disease (Nakanuma stage 2), strong ABCB11, and ABCB4 expression/accumulation at the bile canalicular membrane were only present focally in some periportal hepatocytes (zone 1 hepatocytes, Figure 3 and Supplementary ); in contrast, in liver tissue of PSC patients with advanced cholestatic liver disease (Nakanuma stage 3-4), ABCB11 and ABCB4 were overall strongly expressed and not only focally in periportal hepatocytes (zone 1 hepatocytes), but also in areas around the central vein (zone 2/3 hepatocytes, Figure 3 and Supplementary ). The gene discussed is ABCB4; the disease is pancreatic serous cystadenoma.