Both iNOS and ARG2 proteins were generally expressed at higher levels in the airway epithelium of asthmatics compared with healthy controls [iNOS protein expression relative to cytokeratin expression, control 1.1 ± 0.2, n = 5, asthma 23.9 ± 13.8, n = 10, P = 0.01; ARG2 protein expression relative to cytokeratin expression, control 1.0 ± 0.1, n = 5, asthma 3 ± 1.3, n = 9, P = 0.03](S1 Table). The gene discussed is NOS2; the disease is asthma.