Accordingly, not only is AhR gene expression negatively regulated in patients with inflammatory bowel disease (IBD) [7], but AhR ligands have been proven effective in attenuating inflammation and immune dysfunction in murine models of colitis, while AhR−/− mice are more prone than their wild-type counterparts to develop severe immune dysfunction [8,9,10,11]. The gene discussed is AHR; the disease is colitis.