This study aims to test whether caspase-8, caspase-9 and cytochrome-c are involved in caspase-3-dependent apoptosis induced by kaempferol and quercetin in oral, breast, and colon cancer cells. This paper reports the devised experiments based on cell proliferation assays, flow cytometry, and Western Blot analysis. It also discusses 12 possible results of the experiments as well as their implications on the study of apoptotic mechanism of kaempferol and quercetin.