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Jun 5, 2012
Fluorescence Activated Cell Sorting (FACS) is used to study DNA cell content. Propidium iodide (PI) intercalates into double-stranded nucleic acids and fluoresces. It is excluded by viable cells but can penetrate cell membranes of dying or dead cells. Thus PI staining is included in immunofluorescent staining protocols to identify dead cells. DNA staining can be used to study the cell cycle. Relative DNA content shows the proportion of cells in G1, G2 and S phases. Apoptotic cells show characteristic smear on DNA staining. Here a protocol to stain cells by PI is described.