There was, subsequently, a difference between healthy and COPD subjects’ lung fibroblasts in the IRE1 response (CSE 10%: p = 0.049, 20% p = 0.0004, and 30% p = 0.023 compared to 0%), but not in ATF6, PERK, or CHOP. Here, DDIT3 is linked to chronic obstructive pulmonary disease.