Goblet cell hyperplasia (GCH) is part of airway remodeling in various respiratory diseases, and serves as an important marker of adverse response to lung epithelium challenge. The goblet cells also produce mucins (constituents of mucus) that have involvement in lung diseases. The mucus layer acts as a barrier to trap particulates and contains detoxifying enzymes. The changes in goblet cell numbers and mucus production in RHuA tissues can be assessed by MUC5AC staining and using chromogenic stains (e.g. Alcian blue and Periodic-Acid-Schiff).