MUC5AC and sinusitis: Considering that a marked increase of MUC5AC and MUC5B secretion has been reported in sinus disease, and MUC5AC expression was found to be higher compared to MUC5B in sinus [28], the role of hypoxic stress to mucosal epithelium in the pathophysiology of sinusitis could be an area where greater attention should be paid clinically.