Nat. Chem. Biol. 1, 308–314 (2005)

Some information was omitted from Table 1 of this article. The table should have indicated that the first report of cells (macrophages) generating nitrite and nitrate was published in 1985 by Stuehr and Marletta (Stuehr, D.J. & Marletta, M.A., Mammalian nitrate biosynthesis: mouse macrophages produce nitrite and nitrate in response to Escherichia coli lipopolysaccharide, Proc. Natl. Acad. Sci. USA 82, 7738–7742, 1985).