Produces nitric oxide (NO) which is a messenger molecule with diverse functions throughout the body (PubMed:7504305, PubMed:7531687, PubMed:7544004, PubMed:7682706). In macrophages, NO mediates tumoricidal and bactericidal actions. Also has nitrosylase activity and mediates cysteine S-nitrosylation of cytoplasmic target proteins such PTGS2/COX2 (By similarity). As component of the iNOS-S100A8/9 transnitrosylase complex involved in the selective inflammatory stimulus-dependent S-nitrosylation of GAPDH on 'Cys-247' implicated in regulation of the GAIT complex activity and probably multiple targets including ANXA5, EZR, MSN and VIM (PubMed:25417112). Involved in inflammation, enhances the synthesis of pro-inflammatory mediators such as IL6 and IL8 (PubMed:19688109). {ECO:0000250|UniProtKB:P29477, ECO:0000269|PubMed:19688109, ECO:0000269|PubMed:25417112, ECO:0000269|PubMed:7504305, ECO:0000269|PubMed:7531687, ECO:0000269|PubMed:7544004, ECO:0000269|PubMed:7682706}. This is the function of ENSG00000007171 (NOS2, nitric oxide synthase 2).