HSPA5 and fibrosis: Induction of sXBP1, ATF6N and GRP78 ER stress markers was considered as a common molecular feature of IPF, also observed in BLM-induced lung injury in mice [19,32] The origin of ER stress observed in lung biopsies from IPF patients and mice lung in experimental fibrosis is not completely understood and the implication of a hypoxic microenvironment of AEC cells has been proposed [19,40].