In addition to altered ion and fluid transport that result in a dehydrated mucous layer, the CF airways are characterized by goblet cell and glandular hyperplasia and subsequent overproduction of the two secreted mucins MUC5B and MUC5AC, which has been reported in both CF patients and CF model systems (Henderson et al., 2014; Esther et al., 2019). The gene discussed is MUC5AC; the disease is cystic fibrosis.