CCK-8 is an upgraded product of MTT. CCK-8 solution can be directly added to cell samples without pre-preparing various ingredients. It has rapid detection and very low toxicity. CCK-8 is based on the water-soluble tetrazolium salt WST-8. The working principle is: WST-8 can be reduced by dehydrogenase in mitochondria to produce orange-yellow formazan dye in the presence of electron coupling reagent. The formazan dye is able to dissolve in tissue culture medium in proportion to the number of viable cells. Through colorimetry, the number of viable cells can be dynamically quantified, so as to detect cell proliferation or drug toxicity. This kit is usually used for cycle and apoptosis detection of adherent or suspended cells. If it is used in tissue, the tissue needs to be digested into a single-cell state, and then it can be tested.