As we observed that MUC5B is co-expressed with surfactant protein C in type 2 alveolar epithelia and cells lining honeycomb cysts in human IPF (Fig. 1a, b), we postulate that the cells involved in MUC5B overexpression are involved in the lung remodeling that is characteristic of IPF. This evidence concerns the gene MUC5B and idiopathic pulmonary fibrosis.