Indeed, these immune cells, once entered into the CF airways, produce damaging mediators (proteases, reactive oxygen species, elastase) [100] that induce epithelial apoptosis [101] and/or premature senescence [102], and herald the remodeling of the airway epithelium by upregulating mucin expression and inducing goblet cell metaplasia [103,104]. The gene discussed is MUC5AC; the disease is cystic fibrosis.