What are the similarities between MTT and MTS assays?

MTT and MTS assays share many commonalities. One similarity is that both assays are used to measure cell viability in vitro. Additionally, they both measure the effect that molecules have on cell proliferation and cytotoxicity. They are also both colorimetric assays. Another similarity is both assays measure the metabolic activity of cells based on their ability to create formazan crystals. Both assays also use NADPH as the reduction agent, and both assays need must be performed in the dark due to MTT being a light sensitive reagent. Finally, the incubation times are the same, at 1-4 hours, at 37 degrees Celsius.