MUC5AC and cystic fibrosis: Moreover, abnormalities of mucus and mucus-producing cells in CF have also been observed, although during the progression of lung diseases, including increased luminal mucus (with increased amounts of DNA derived from neutrophils), abnormal amounts of mucins (MUC5AC, MUC5B, and MUC2), goblet cell hyperplasia, and submucosal gland hypertrophy [9] (Figure 1).