The constitutive androstane receptor (CAR) is a nuclear receptor that functions as a sensor of toxic compounds and enhances their elimination. CITCO is an agonist of human CAR (EC50 = 49 nM). It induces nuclear translocation of human CAR in hepatocytes, followed by increased expression of CAR-regulated genes, including several cytochrome P450 isoforms. CITCO less potently activates human pregnane X receptor (EC50 = 3 μM) and has no detectable activity on other nuclear receptors at 10 μM. It is selective for human CAR, whereas TCPOBOP is selective for mouse CAR. CITCO does activate alternative splice variants of human CAR that are also found in liver cells. It is commonly used to study the action of human CAR in hepatocytes.
