P 2815 (OTTO) Pyronin G(Y) Cas 92-32-0 - used to ascertain the cell cycle state of stem cells and is amenable to flow cytometry. P 2815 (OTTO) Pyronin G(Y) Cas 92-32-0 - used in living cell preparations, it is commonly combined with 50-100 µM verapamil to prevent efflux of the dye.