Toxic substance (i.e. PTC) activates bitter taste receptor, T2R38 leading to release of gut hormones. CCK released from the basal surface of the enteroendocrine cells, increases through paracrine signaling expression of efflux transporter, ABCB1 in the enterocytes, resulting in rapid excretion of bitter or dietary toxin. EEC, enteroendocrine cells; EC, enterocytes.