Detect apoptosis and membrane permeability with the Annexin V-FITC Apoptosis Assay Kit. This in vitro apoptosis assay employs the green fluorescent Annexin V-FITC reagent to label exposed phosphatidylserine in cultured cell samples. Detect membrane compromised cells, a trademark of late apoptosis or cell necrosis, with the live/dead stain, propidium iodide. Analyze the fluorescent signals by flow cytometry.