Inducible nitric oxide synthase (iNOS) is a widely expressed, approximately 130 kDa enzyme that catalyzes the conversion of L-arginine to nitric oxide (NO) plus citrulline. NO is a bioactive mediator that plays an important role in hemodynamics by inducing vascular smooth muscle relaxation. iNOS is constitutively expressed in the kidney. In other tissues, it is inducibly expressed during inflammation, oxidative stress, and hyperglycemia. iNOS activity is elevated in a variety of disease states including atherosclerosis, heart failure, sepsis, solid tumors, and type 2 diabetes. Increased production of NO mediates acute kidney injury, TNF-alpha induced muscle wasting, and the increased radiosensitivity of hypoxic tumor cells. Within amino acids 781-798, human iNOS shares 89% and 72% aa sequence identity with mouse and rat iNOS, respectively.