Detection of apoptosis with annexin V/propidium iodide (PI) staining

Detection of apoptotic cells was done with fluorescein isothiocyanate- or allophycocyanin-labeled annexin V (BD Biosciences, Franklin Lakes, NJ, USA) and PI (Hoffman-La Roche, Basel, Switzerland), as described [53]. Apoptotic cells were analyzed on a BD FACSCalibur flow cytometer (BD Biosciences). Early apoptotic cells were stained with annexin V but not PI, whereas late apoptotic or necrotic cells were stained with both annexin V and PI.