DOJINDO is the original creator of WST dyes and Cell Counting Kit-8 (CCK-8). CCK-8 has been used by researchers all over the world for over 20 years. The reasons for this include 1) reliable and stable quality, 2) long-term stability (1 year: 0-5°C, 2 years: -20°C), 3) higher sensitivity than MTT, XTT, MTS, or WST-1, and 4) low toxicity to cells, a combination of features that have been improved over its long history and that no other company can imitate. CCK-8 enables sensitive colorimetric assays to determine cell viability in cell proliferation and cytotoxicity assays. The kit includes Dojindo's WST-8 which is reduced by dehydrogenase activity in cells to give a yellow-colored formazan dye. The amount of the dye, generated by the activity of dehydrogenases in cells, is directly proportional to the number of living cells. visit the supplier website at “https://dojindo.com/product/cell-counting-kit-8/”.