HERPUD1 and chronic obstructive pulmonary disease: 2010a), before and after addition of a stressor (fold change in expression compared to baseline is presented in Fig. 5). Overall, in most subjects there was an upregulation of ER stress response genes after addition of stressor compared to baseline, i.e., the fold change is >1 (Fig. 5). In addition, significant differences in stress response were seen between never‐smoker, ever‐smoker, and COPD cells in ERP72 under stress by Brefeldin A and thapsigargin (Fig. 5C). No significant changes were observed in BiP, HERPUD1, or WARS expression after any stressor.