The polyanionic dye ANTS is often used in combination with the cationic quencher DPX (X1525) for membrane fusion or permeability assays, including complement-mediated immune lysis. The unusually high Stokes shift of ANTS in water (>150 nm) separates this from much of the autofluorescence of biological samples. ANTS has also been employed as a neuronal tracer.