Figure 2.

The CFP-DEVD-YFP fusion protein in HeLa-C3 cells is specifically cleaved during apoptosis but not necrosis. HeLa-C3 cells were treated with either an apoptotic inducer (5 min UV-irradiation) or a necrotic stimulus (5 mM H₂O₂) for various times and analyzed by Western blotting (a) and agarose gel electrophoresis (b). The cleavage of sensor protein was observed only during UV-induced apoptosis as indicated by caspase-3 activation (a) and DNA fragmentation (b). (c) HeLa-C3 cells grown in a 96-well plate were irradiated with 5 min UV light and then cultured for 9 h or treated with 5 mM H₂O₂ for 8 h. After detecting the fluorescence intensity of the cells using a fluorescent plate reader, cell viability was determined from the same sample well by MTT assay. Data shown are means±s.d. from three experiments.