Chemical. CAS 3520-43-2 and 47729-63-5. Formula C25H27Cl4IN4. MW 652.2. The membrane-permeant dual-emission potential-sensitive JC-1 dye is widely used in apoptosis studies to monitor mitochondrial health by flow cytometry, fluorescence microscopy and in microplate-based fluorescent assays. JC-1 dye can be used as an indicator of mitochondrial membrane potential in a variety of cell types, including myocytes and neurons, as well as in intact tissues and isolated mitochondria. JC-1 accumulates in mitochondria, selectively generating an orange J-aggregate emission profile 590 nm in healthy cells. After cell injury, as membrane potential decreases, JC-1 monomers are generated, resulting in a shift to green emission 529 nm. The principal advantage of JC-1 relative to other commonly employed fluorescent probes of mitochondrial membrane potential is that it allows qualitative visualization, considering the shift from orange to green fluorescence emission.