DDIT3 and Bloom syndrome: Immunochemical staining (Figures 2(a)–2(c)) of ER stress markers in the alveolar region revealed decreased expression of Grp78 in the BLM model group, while expression of Grp94 and CHOP increased, suggesting that loss of the chaperone protein Grp78 promoted ER stress, which was consistent with previous reports [23].