Pyronin Y is a fluorescent probe which stains double stranded RNA in living or fixed cells as well as in tissues. When used in living cell preparations, it is commonly combined with 50-100 μM verapamil to prevent efflux of the dye. It has been used to ascertain the cell cycle state of stem cells and is amenable to flow cytometry. Maximum excitation is at 540-550 nm, with maximum emission at 560-580 nm.
