Figure 3: Function of CAR and PXR in xenobiotic metabolism. CAR and PXR are activated by specific xenobiotics (X). In turn they dimerize with RXR, act on consensus sequences (XREM/PBREM), and initiate transcription of phase I and II enzymes involved in the hydroxylation and conjugation of xenobiotics, and phase III transporters that eliminate the xenobiotics. Indirect activatin of CAR and its subsequent translocation to the nucleus is key in its transcriptional activity.