Anti-NADPH Oxidase 4 antibodies are used in the immunodetection of the protein encoded by the NOX4 gene. In humans, the canonical protein has a reported length of 578 amino acid residues and a mass of 66.9 kDa. Its subcellular localization is in the ER and cell membrane. Alternative splicing is reported to yield 9 different isoforms for this protein. It is noted to be expressed by distal tubular cells in kidney cortex and in endothelial cells. The NADPH oxidase 4 protein is involved with cardiac muscle cell differentiation and carbohydrate metabolism and homeostasis, among other functions. Post-translational modifications have been described, including N-glycosylation. Other names for this target antigen include KOX-1, RENOX, kidney oxidase-1, kidney superoxide-producing NADPH oxidase, renal NAD(P)H-oxidase, and KOX.