The study of cell viability and proliferation is very important for evaluating a cell population's responses to external factors, such as growth factors, antibiotics and anti-cancer drugs. The ScienCellTM MTT Cell Viability & Proliferation Assay allows simple, accurate and reliable counting of metabolically active cells, based on the conversion of pale yellow tetrazolim MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] to purple formazan crystals. The crystals can be solubilized and then spectrophotometrically quantified.