Previous studies found that the assembly of cilia is remarkably decreased but the secretion of mucins (encoded by MUC5AC and MUC5B) is increased in COPD, asthma, IPF, and cystic fibrosis (Benam et al., 2018; Samsuzzaman et al., 2019). Here, MUC5AC is linked to idiopathic pulmonary fibrosis.