ATP8B1 and Cholestatic liver disease: Other canalicular transporters and their regulators are implicated in the pathogenesis of cholestatic liver disease e.g. ATP8B1 (a P-type ATPase that flips phospholipids into the cytoplasmic leaflet of the membrane)3, NR1H4 (farnesoid X receptor (FXR)) gene5, and TJP2 (tight junction protein 2)6.