[5][6] The protein encoded by this gene is a cytosolic regulatory component of the superoxide-producing phagocyte NADPH-oxidase, a multicomponent enzyme system important for host defense.

It interacts primarily with neutrophil cytosolic factor 2 (NCF2/p67-phox) to form a complex with neutrophil cytosolic factor 1 (NCF1/p47-phox), which further interacts with the small G protein RAC1 and translocates to the membrane upon cell stimulation.

This complex then activates flavocytochrome b, the membrane-integrated catalytic core of the enzyme system.

Alternatively spliced transcript variants encoding distinct isoforms have been observed.

[7] Crohn's patient with rs4821544 variants showed a decreased reactive oxygen species after stimulation with GM-CSF which is a proinflammtory cytokine.