HNF4A and irritable bowel syndrome: We briefly summarized the roles in IBD of several other NRs (Table 2), including Nur77 (NR4A1) [106, 107], liver receptor homolog 1 (LRH-1/NR5A2) [108, 109], liver X receptor (LXR/NR1H) [110], constitutive androstane receptor (CAR/NR1I3) [111], hepatocyte nuclear factor-4 alpha (HNF4α/NR2A1) [112–114], and NR2F6 [115].