Reining in H(2)O(2) for safe signaling.
Mammalian cells use hydrogen peroxide (H(2)O(2)) not only to kill invading pathogens, but also as a signaling modulator. Woo et al. (2010) now show that the local inactivation of a H(2)O(2)-degrading enzyme ensures that the production of this oxidant is restricted to the signaling site.