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. This protein is preferentially expressed in cells of myeloid lineage. 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. The PX domain of this protein can bind phospholipid products of the PI(3) kinase, which suggests its role in PI(3) kinase-mediated signaling events. The phosphorylation of this protein was found to negatively regulate the enzyme activity. Alternatively spliced transcript variants encoding distinct isoforms have been observed.NCF4 (Neutrophil Cytosolic Factor 4) is a Protein Coding gene. Diseases associated with NCF4 include Granulomatous Disease, Chronic, Autosomal Recessive, Cytochrome B-Positive, Type Iii and Chronic Granulomatous Disease. Among its related pathways are Toxoplasmosis and Blood-Brain Barrier and Immune Cell Transmigration: VCAM-1/CD106 Signaling Pathways. GO annotations related to this gene include protein dimerization activity and phosphatidylinositol-3-phosphate binding.