In AECs of IPF patients, there was a notable rise in the levels of various ER stress markers, including ATF4, ATF6, CHOP BiP, EDEM, and XBP1, particularly observed in type II AECs (Korfei et al., 2008; Lawson et al., 2008). Here, ATF4 is linked to idiopathic pulmonary fibrosis.