ATF6 and PERK was decreased in response to increasing concentrations of CSE, more so in lung fibroblasts from COPD subjects (ATF6: CSE 5% p = 0.030, 10% p = 0.099, 20% p = 0.028, 30% p = 0.0031, and PERK: CSE 5% p = 0.074, 10% p = 0.0079, 20% p = 0.0002, 30% p < 0.0001 compared to 0%), but also in lung fibroblasts from healthy subjects (ATF6: CSE 10% p = 0.063 and 30% p = 0.10, and PERK: CSE 20% p = 0.0036, 30% p = 0.0024 compared to 0%). Here, ATF6 is linked to chronic obstructive pulmonary disease.