This reduction in metabolic viability corresponded to an increase in apoptosis induction, as DRE treatment triggered apoptosis selectively in colon cancer cells, but not in normal mucosal cells, which was subsequently confirmed by fluorescence microscopy following Hoechst 33342, propidium iodide and Annexin V staining, to observe the nuclear morphology, cell membrane integrity and externalization of phosphatidylserine respectively. In the DRE-treated colon cancer cells we observed significant increases in propidium iodide and Annexin V positive staining, indicative of apoptosis, while NCM460 cells, again, remained unaffected (Figure (Figure1B).1B). Image-based cytometry was used to quantify the apoptotic response and the data showed an approximately 40% increase in Annexin V positive cells and a corresponding 97% increase in propidium iodide staining in DRE responsive cells (Figure (Figure1C).1C). These results confirmed the anti-cancer potential of DRE and demonstrated its efficacy in aggressive colorectal cancer cells regardless of their p53 status.