Can apoptosis be detected by cell cycle studies?

A cell cycle study cannot distinguish cells undergoing apoptosis from those undergoing necrosis. A better method to detect apoptosis may be to conduct a DNA ladder assay or TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) assay to check for fragmentation. Another option may be to conduct an Annexin V/PI assay; early apoptotic cells will stain positive for Annexin V but negative for PI (propidium iodide), allowing them to be distinguished from late apoptotic cells and necrotic cells, which will stain positive for both Annexin V and PI.