CytoScan™ WST-1 Cell Proliferation Assay is a sensitive and accurate assay for cell proliferation and cytotoxicity.  The assay is highly convenient as it is performed in a single cell tissue culture well and requires no washing, harvesting or solubilization of cells.  Adherent or suspension cells are cultured in a microplate and then incubated with WST-1 and the assay is monitored with a spectrophotometer. The assay principle is based upon the reduction of the tetrazolium salt WST-1 to formazan by cellular dehydrogenases (see figure below).  The generation of the dark yellow colored formazan is measured at 420-480nm (optimal at 440nm) and is directly correlated to cell number. The kit components are sufficient for performing up to 500 assays.