ER stress and UPR signaling are involved in fibrosis through the induction of cell death, myofibroblast transdifferentiation, EMT, and inflammatory responses.[473, 474, 475] ER stress has been found in patients with pulmonary fibrosis.[476] Several aetiologies, such as viral infection, aging, and amiodarone, contribute to UPR activation in the lung.[477, 478] Some disease‐related mutations, such as surfactant protein 2A (SFTPA2) and SFTPC, are associated with IPF.[479, 480, 481] UPR activation was found in AEC2s with SFTPC mutation in patients with pulmonary fibrosis. This evidence concerns the gene SFTPC and idiopathic interstitial pneumonia.