MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) is a tetrazolium salt that is commonly used to detect reductive metabolism in cells for viability, proliferation and cytotoxicity assays. On reduction tetrazolium salts turn into deeply colored products that can be easily quantified by colorimetric measurement. MTT forms a purple formazan product that needs to be solubilized prior to quantification. MTT is useful for high throughput screening of antiviral and anticancer compounds and for the studies of cytokine effect on cell proliferation. Please also see the MTT Cell Proliferation Assay Kit.