MUC5AC and ulcerative colitis: MUC5AC mucin, which is normally expressed in mucosa of the intestines and airway, was shown to be up-regulated in both T. muris infections and human ulcerative colitis, and blocking of ectopic MUC5AC expression was identified as a likely contributor in the effectiveness of oral tacrolimus therapy in patients with refractory ulcerative colitis [38,39].