XBP1 and idiopathic pulmonary fibrosis: Expressions of heavy-chain binding protein (Bip), Endoplasmic Reticulum degradation-enhancing α-mannosidase-like protein (EDEM), X-box binding protein 1 (XBP1), Activating transcription factor 4 (ATF4), Activating transcription factor 6 (ATF6) and CHOP were increased in Alveolar Epithelial Cells (AEC) of IPF patients, accompanied by Caspase-3-induced apoptosis39,40.