Therefore, in the present study, we first examined changes in the protein expression of NOX isoforms NOX1, NOX2, NOX4, and NOX5 in lung sections of human COPD patients undergoing lung transplantation; and then investigated the roles of NOX isoforms in regulating oxidative stress and lung inflammation in mice exposed to acute cigarette smoke. Here, CYBB is linked to chronic obstructive pulmonary disease.