Semiquantitative assessment of positive staining to eNOS showed that eNOS expression in pulmonary arteries of patients with hypoxemic COPD was significantly lower than that of control subjects and patients with nonhypoxemic COPD (P < 0.05 and P < 0.05, respectively) (Fig. 2A). The gene discussed is NOS3; the disease is chronic obstructive pulmonary disease.