Description
Proliferation assays are widely used in cell biology to assess the effects of growth factors, cytokines, nutrients, and cytotoxic agents on cells. Viable cell numbers are assessed in two main ways: 1) directly, by counting cells with a microscope or an electronic particle counter, or 2) indirectly, by measuring the incorporation of radioactive precursors, quantifying total protein with chromogenic dyes, or assessing metabolic activity of cellular enzymes. The NAPTiter Cell Proliferation Assay uses specialized reagents to quickly and conveniently assess cell proliferation, cytotoxicity, cell attachment, chemotaxis, and apoptosis in adherent and suspension cells without protocol modifications. An optimized Dye Solution is added to culture wells in a 96-well plate, which typically contains various concentrations of a growth factor or test substance to conduct the assay. During a 4-hour incubation, living cells convert the tetrazolium component of the Dye Solution into a formazan product. The Solubilization/Stop Solution is then added to lyse the cells and dissolve the formazan product, after which the absorbance is measured at 570 nm using a 96-well plate reader. If a 570 nm filter is unavailable, filters between 560-600 nm can also be used. Although the formazan product has an absorbance maximum at 570 nm and appears blue in pure solutions, the final color may vary based on the amount of formazan relative to other culture medium components, such as serum, acidified phenol red, and unreduced MTT.