NOS2 (nitric oxide synthase 2) is an inducible enzyme that catalyzes nitric oxide (NO) production, functioning as a critical immunomodulator with pleiotropic effects. In macrophages, NOS2-derived NO mediates tumoricidal and bactericidal actions 1234. Beyond NO synthesis, NOS2 possesses nitrosylase activity, mediating cysteine S-nitrosylation of cytoplasmic proteins including PTGS2/COX2 and components of the GAIT complex 5. NOS2 bridges inflammatory responses and metabolic pathways, with LACC1 serving as a functional bridge between NOS2 and polyamine metabolism in inflammatory macrophages 6. NOS2 expression enhances pro-inflammatory mediator synthesis including IL-6 and IL-8 7. In disease contexts, NOS2 exhibits dichotomous roles: in tumors, proinflammatory macrophage-derived NOS2 can initiate tumor cell apoptosis through p53 accumulation, though tumor microenvironment hypoxia attenuates this cytotoxic activity 8. NOS2 is overexpressed in aggressive ovarian and prostate cancers, promoting angiogenesis and proliferation while potentially sensitizing tumors to chemotherapy 9. In glioblastoma, NOS2 inhibition reduces proliferation, migration, and neurosphere generation 10. NOS2 deficiency increases susceptibility to central nervous system tuberculosis, highlighting its protective antimicrobial role 11. Clinically, NOS2 expression distinguishes psoriasis from eczema diagnosis 12, suggesting biomarker potential in inflammatory skin diseases.