Fig. 2From: Highlighting the gaps in hazard and risk assessment of unregulated Endocrine Active Substances in surface waters: retinoids as a European case studyHeterodimerization partners of the retinoid X receptor (RXR). Non-permissive heterodimers require ligand binding to the non-RXR monomer to elicit transcriptional activity, while monomers of the permissive heterodimers act in a cooperative synergistic fashion. This can greatly amplify the response to certain ligands in presence of synergistic RXR ligands and exaggerate the transcriptional response. CAR: constitutive androstane receptor, FXR: farnesoid X receptor, LXR: lipid X receptor, Nur77: nuclear receptor subfamily 4 variant 77, Nurr1: nuclear receptor related 1 protein, PPAR: peroxisome proliferator-activated receptor, PXR: pregnane X receptor, RAR: retinoic acid receptor, TR: thyroid hormone receptor, VDR: vitamin D receptorBack to article page