The Astral Viability Assay combines a cytoplasmic FITC-detectable live cell dye with a DAPI-detectable dye that labels the nucleus of all cells. The all-cell nuclear dye can be used to normalize for cell number. The cytoplasmic dye readily enters live cells producing a highly fluorescent, well-retained, FITC-detectable dye that has little effect on intracellular processes. Dying and dead cells do not retain the fluorescent dye due to compromized cell membranes.