MUC5AC and nasal cavity polyp: For example, fluticasone propionate significantly reduced MUC5AC protein expression in the human lung mucoepidermoid carcinoma cell line (H292 cells) [11], whereas a treatment with dexamethasone did not change significantly the steady-state messenger ribonucleic acid (mRNA) levels of MUC5AC in cultured human nasal epithelial cells obtained from nasal polyps [12] and even enhanced both MUC5AC protein secretion and MUC5AC mRNA expression in cultured normal human bronchial epithelial cells [13–15].