Apoptosis assay

PC3 cells were treated with MnTE-2-PyP overnight prior to irradiation of 20 Gy. Cells were harvested 48 hours after irradiation, fixed with 4% paraformaldehyde for 30 minutes. The cells were TUNEL stained using the In Situ Cell Death Detection Kit, Fluorescein (Roche, Mannheim, Germany) and then analyzed by fluorescence-activated cell sorter (FACS) (FACScalibur; Becton Dickinson Immunometry Systems, San Jose, CA). Fluorescence data, which indicated TUNEL positive cells, were collected on a log scale, with green fluorescence measured at 530 nm. Data from 10,000 events (cells) were collected and analyzed with CellQuest software (Becton Dickinson Immunometry Systems).