The three core transmembrane proteins in TJs, junctional adhesion molecule (JAM), occludin and claudins seal the hepatocytes. The TJs segregate the membrane of the hepatocytes into basolateral and apical membrane. At the basolateral (sinusoidal) membrane: ABCA1, ABCC1 (MRP1), ABCC3 (MRP3) and ABCC6 (MRP6) are expressed. At the apical (canalicular) membrane: ABCB1(MDR1), ABCB4 (MDR3), ABCB11 (BSEP), ABCC2 (MRP2), ABCC4 (MRP4, which localisation in hepatocytes is controversial), ABCG2 (BCRP) and ABCG5/G8 are expressed. (Tight junctions; TJs, ATP-binding cassette; ABC, multidrug resistance-associated protein; MRP, multidrug resistance; MDR, bile salt export pump; BSEP, breast cancer resistance protein; BCRP)