Using RNA interference, we found that Apollon knockdown significantly potentiated cisplatin or doxetacel-induced apoptosis, mitochondrial membrane potential collapse, cytochrome c release, caspase activation, and long-term cell growth suppression, hence sensitizing esophageal cancer to cisplatin or doxetacel treatment in vitro and in vivo. This evidence concerns the gene CYCS and esophageal cancer.