ABCB4 and Hepatic fibrosis: However, since Abcb4−/− mice suffer from defective bile formation (i.e., the lack of biliary phospholipid secretion with consecutive toxic bile formation) and norUDCA also has substantial effects on bile formation and composition [14], [15], it remains unclear whether this promising compound is able to exert beneficial mechanisms in non-cholestatic types of liver fibrosis.