FIG. 1.

Activation and production of superoxide by reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (Nox2). Catalytically functional Nox2 complex requires the assembly of membrane-bound gp91^phox and p22^phox, with cytosolic subunits p67^phox, p47^phox, p40^phox, and Rac1/2. Active Nox2 complex catalyzes the oxidation of NADPH, releasing electrons that convert oxygen molecules to superoxide. Activation of several signaling kinases can promote the assembly of the Nox2 complex through phosphorylation of gp47phox subunits.