Chemical structures of ligands for PXR including pregnane and androstane steroid hormones, bile salts (including an ‘early’ bile salt typical of the earliest bile salts to evolve in vertebrates), the experimental cholesterol-lowering drug SR12813, and the putative endogenous benzoate ligand of the Xenopus laevis BXRα. Note that some of the PXR activators are also agonists of VDR or CAR or, in the case of 5α-androstanol, inverse agonists of human and mouse CAR.