CF bronchial epithelial cells co-cultured with neutrophils (Meng et al., 2000) or stimulated with cytokines (Meng et al., 1998) showed no increase in iNOS expression in contrast with normal bronchial epithelial cells, suggesting that this lack of NO plays an important role in bacterial colonization and neutrophil infiltration. Here, NOS2 is linked to cystic fibrosis.