Mucin family members, including MUC4, play important regulatory roles in proliferation, epithelial to mesenchymal transition (EMT), fibroblast to myofibroblast transition (FMT), tissue remodeling and fibrosis as observed in diseases such as idiopathic pulmonary fibrosis (IPF) and cancer (72–74). Here, MUC5AC is linked to idiopathic pulmonary fibrosis.