MTT Formazan is widely used in biological and medical research as a key indicator in cell viability and proliferation assays. It is formed when the yellow tetrazolium salt MTT is reduced by metabolically active cells, particularly in the mitochondria. The resulting purple formazan crystals are insoluble in water but can be solubilized using solvents like dimethyl sulfoxide (DMSO) or isopropanol. The intensity of the color produced is proportional to the number of viable cells, making it a valuable tool for assessing cell health, cytotoxicity, and the effects of drugs or other compounds on cell growth. This method is commonly applied in cancer research, drug screening, and toxicology studies due to its reliability and ease of use.