Other reactive oxidants generated by lung cells include but are not limited to (1) superoxide from NADPH oxidase 2 (NOX2) [89], (2) superoxide from an uncoupled mitochondrial electron transport chain [90], (3) superoxide from xanthine oxidase, (4) hydroxyl radical from the Fenton reaction, (5) endothelial nitric oxidase synthase uncoupling [91], et al. The decreased glutathione metabolism further supports the mechanistic role of OS in BPD [92]. This evidence concerns the gene CYBB and bronchopulmonary dysplasia.