Characterization of the Cellular Reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT): Subcellular Localization, Substrate Dependence, and Involvement of Mitochondrial Electron Transport in MTT Reduction

The MTT assay, which is widely used to measure cell proliferation and to screen for anticancer drugs, is based on reduction of the tetrazolium salt, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) by actively growing cells to produce a blue formazan product. Despite broad acceptance of this assay, neither the subcellular localization, nor the biochemical events involved in MTT reduction are known. Mitochondrial involvement in...