Cell proliferation can be detected by a variety of methods. Cell proliferation induces an increase in the activity of the mitochondrial dehydrogenases, which cleaves the tetrazolium salt to formazan.

 The WST Cell Proliferation Colorimetric Assay Kit plus provides the easiest and most sensitive way for quantification of cell proliferation and viability. Cell proliferation causes the increase in the amount of formazan dye formed that is directly proportional to the number of living cells and can be quantified by measuring the absorbance of the dye solution at 440 nm using microtiter plate reader. The kit can be used for the analysis of cell proliferation in response to pharmaceutical compounds, cytotoxic compounds like anticancer drugs and many other toxic agents. The assay can also be used for the detection of cell proliferation in response to cytokines, mitogens, growth factors and nutrients, etc. The assay is very easy and simple, just add-and-read, requiring no solubilization, no washing and no harvesting steps, and is stable, faster and more sensitive than MTS, MTT or XTT-based assays. The entire assay can be performed in a microtiter plate and correlates well with the [3H]-thymidine incorporation assay.