The need for a reliable, sensitive and quantitative assay that would enable analysis of a large number of samples led to the development of methods, such as:

• use of radioactive thymidine to label DNA in live cells
• use of Brdu to label DNA in live cells (as a substitute for radioactive thymidine)

The advantages of using MD Bioproducts Cell Proliferation Kit (XTT) can be summarized with the following attributes:

• easy-to-use: there is no requirement for additional reagents and/or the cell washing procedures
• speed: multiwell plates and an ELISA reader can be used for reading
• sensitivity: can be assayed even in low cell concentrations
• accuracy: dye absorbance is proportional to the number of cells in each well
• safety: there is no need for radioactive isotopes