Annexin V/PI Staining of HNSCC cells.

<p>Results obtained by fluorescence microscopy show that early apoptotic cells have bound Annexin-FITC to the phosphatidylserin on the membrane surface (green cell). As apoptosis progressed, the plasma membrane integrity gets lost, and the propidium iodide is able to bind to nucleotid DNA, so that late apoptotic or necrotic cells appear in red.