TP53 and cancer: Therefore, downregulation or upregulation of Bcl-2 or p53, respectively, in ETBO-treated cancer cells could promote the release of mitochondrial cytochrome c and activate the caspase cascade; p53 activation can trigger cytochrome c release into the cytoplasm via the Bcl-2-mediated pathway, and the released cytochrome c activates caspase-3.