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. The gene discussed is NOX5; the disease is chronic obstructive pulmonary disease.