ATP8B1 and intrahepatic cholestasis: Secretion depends on the amount of cholesterol and lipids in the membrane, which can be altered by the flippase familial intrahepatic cholestasis-1 (FIC, coding gene: ATPase phospholipid transporting 8B1; ATP8B1) and the flippase multidrug resistance protein (MDR3, coding gene: ATP binding cassette subfamily B member 4; ABCB4).