Propidium iodide membrane integrity assay pLuc705 cells were seeded 20 h before treatment in 12-well plates at 100 000 cells/well. Cells were treated by removing the medium, washing with 500 ml PBS and incubating with medium containing CPPÀPMO conjugates. Treatment medium was collected in tubes and cells were washed with PBS once, and then treated with 400 ml of 10% trypsin for 10 min at 378C. Trypsin was neutralized with 500 ml of the serum containing medium. Cells were transferred to the tubes containing previously collected treatment medium, pelleted by centrifugation at 1000g for 5 min, washed with PBS once, and re-suspended in 200 ml of 0.05 mg/ml propidium iodide (PI) in PBS. Cells were further incubated at 378C for 15 min and analyzed by the Beckman Coulter cytometer (30 000 events/sample collected).