MUC5B and idiopathic pulmonary fibrosis: In addition, during differentiation, control and IPF epithelia present distinct differences in cellular differentiation (MUC5B+ cells), composition (MUC5B+ and KRT5+ cells), and epithelial integrity (transepithelial electrical resistance (TEER)), but not in proliferation (Ki67) or basal cell subtypes (KRT5, KRT8 and P63+ cells) (Supplementary Fig. 1 A–E).