The cell suspensions were subjected to flow cytometry data analysis (BD FACScan) to differentiate between live or viable cells (Annexin V−/PI−), early apoptotic cells (Annexin V+/PI), necrotic cells (Annexin V−/PI+), and late apoptotic-necrotic cells (Annexin V+/PI+). The data were confirmed by ImageStream multispectral flow cytometry analysis (Amnis Corporation, Seattle, WA) with a photo snapshot of each cell passing through the flow chamber as reported previously (Hamidu et al., 2010).