Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a 37 kDa enzyme that plays an important role in glycolysis, thus serving to break down glucose for energy and carbon molecules. It is present in high levels in almost all tissues and is thought to be a ubiquitously expressed housekeeping gene. GAPDH has also been described in non-metabolic processes, including DNA replication, RNA transport, transcription activation, apoptosis initiation, and the shuttling from the endoplasmic reticulum to the Golgi body. GAPDH catalyzes the reversible, oxidative phosphorylation of glyceraldehyde 3-phosphate to D-glycerate 1,3-bisphosphate in the presence of inorganic phosphate and nicotinamide adenine dinucleotide (NAD+) in two coupled steps. D-glycerate 1,3-bisphosphate is an important intermediate used for the synthesis of ATP. GAPDH is reported to bind to other proteins, including the amyloid precursor protein, which has been implicated in Alzheimer’s disease; as well as the polyglutamine tracts of Huntington, which are causative of Huntington’s disease. This kit provides the assay-specific components for the quantitative determination of GAPDH in human and non-human primate samples.