Nature Rev. Microbiol. 2, 593–602 ( 2004)

Reference 105 was erroneously deleted from the reference list of this article and should be:

105. Lundberg, J. O. & Govoni, M. Inorganic nitrate is a possible source for systemic generation of nitric oxide. Free Radic. Biol. Med. 37, 395–400 ( 2004).

The online version of this article has been corrected.