Based on these findings, the role of YAP in the pathogenesis of cholestatic liver disease was investigated in a greater detail, using its specific inhibitor verteporfin (VP) to prevent biliary fibrosis in the Abcb4-/- mice, which lack the ability to secrete phospholipids into the bile from the liver, representing a prototypical animal model of sclerosing cholangitis. This evidence concerns the gene ABCB4 and sclerosing cholangitis.