Enterohepatic circulation of bile acids showing the individual transport proteins in hepatocytes, ileocytes (ileal enterocytes), and renal proximal tubule cells. The reactions depicted in this pathway provide a continuous supply of bile acids, which are required for the digestion of food. This transport system also reduces fecal and urinary bile acid loss, while also restricting these potentially cytotoxic compounds to reach intestinal and hepatobiliary compartments.