NOS2 and in situ carcinoma: It can regulate many hypoxia-related genes such as vascular endothelial growth factor, glucose transporter, erythropoietin, inducible nitric oxide synthase, B-cell lymphoma gene 2, caspase, adenovirus interfering protein 3, Ngb, heat shock protein 70, etc., and these genes increase ATP release by promoting anaerobic metabolism, promote the reconstruction of microcirculation and vasodilation, promote erythropoiesis, increase oxygen-carrying capacity, reduce nerve cell apoptosis, etc., and reduce brain tissue injury after CIS [17].