Since oxidative stress induces ER stress [4], GPx-1 expression is reduced in the COPD lungs [13], and GPx-1 deficiency increases susceptibility to cigarette smoke-induced emphysema [13, 17], we examined whether GPx-1 expression was altered in fully differentiated NHBE cells isolated from nonsmokers, smokers, and COPD donors (Figure 3). Here, GPX1 is linked to pulmonary emphysema.