Apoptosis was also assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay using an in Situ cell death detection kit from Roche Diagnostics. Experiments were carried out in accordance with the manufacturer's recommended procedures. Briefly, JPE treated HCT-116 cells grown on glass coverslips were fixed with 4% paraformaldehyde in PBS and were permeabilized with 0.1% Triton X-100 in 0.1% sodium citrate in PBS. They were then stained with the TUNEL reaction mixture and finally examined using a fluorescence microscope. At least 400 cells per treatment were counted and the results are expressed as percentage apoptosis (% ratio of apoptotic cells/total cells). The experiment was performed in duplicate and data are expressed as means˘S.E.