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Propidium iodide (or PI) is a fluorescent intercalating agent that can be used to stain cells.
P 4336 (OTTO) Propidium iodide, 94%, suitable for cell culture Cas no 25535-16-4 - used in flow cytometry to evaluate cell viability when used with other dyes that stain viable cells or cells that are early in the apoptosis process.