This was important because 5-ASA has been shown to be the active moiety of sulfasalazine in preventing human UC [3] and proctitis [4] and because sulfasalazine but not 5-ASA has been shown to be an inhibitor of the proinflammatory nuclear factor, nuclear factor kappa B (NF-κB) [26]. The gene discussed is NFKB1; the disease is proctitis.