Signosis’ WST-8 Reagent is a colorimetric assay that provides a simple and accurate method to measure cell viability and proliferation. This is a tetrazolium reduction assay based on the cleavage of the tetrazolium salt WST-8 to a water-soluble, orange formazan dye by cellular mitochondrial dehydrogenases. The intensity of the dye is directly proportional to mitochondrial dehydrogenase activity and is used as an indicator of cell viability. The color produced by formazan can be quantified by measuring the absorbance at 450nm.