In addition to RARs, RXRs are capable of dimerizing with numerous non-RAR nuclear receptors, including LXRα (NR1H3), FXR (NR1H4) and PXR (NR1I2) [53], who were all found to be downregulated in the epithelial compartment during active IBD. Here, RARS1 is linked to inflammatory bowel disease.