Hello Alessandra Serain

Yes, you should use MTT assay because of the mode of action of the candidate substance. The CCK-8 assay involves most of the dehydrogenases in a cell. But MTT assay involves mitochondrial dehydrogenase. Therefore, the MTT assay depends on the mitochondrial activity and not the cell itself. So, since the substance promotes mitochondrial apoptosis, you should use MTT assay in this case. Though CCK-8 assay is more sensitive than MTT assay, using MTT assay will be the right assay to check the potency of the candidate substance because of its mode of action.

Best.

The major difference between CCK-8 and the MTT assay, other than MTT's toxicity, is the enzymes involved. The CCK-8 assay involves most of the dehydrogenase in a cell. On the other hand, MTT only involves mitochondrial dehydrogenase. Therefore, the MTT assay depends on mitochondrial activity, not the cell itself.