Calcein-AM is a hydrophobic non-fluorescent probe that can permeate the plasma membrane and can be hydrolyzed to calcein (sc-202090). Calcein-AM is an extremely fluorescent and negatively charged molecule. The Calcein-AM probe can be used to stain living cells and has been observed to fluoresce bright green in cytoplasmic Schwann cells. Calcein-AM has been reported to be a neutral substrate for Mdr (P-glycoprotein (Pgp) and multidrug resistance protein (MRP)) and has been used in flow cytometry studies to analyze the function of P-gp and MRP. Studies suggest that Calcein-AM can be used to detect MDR mediated resistance and to be transported by PGP from the plasma membrane. Mitochondrial permeability research has utilized Calcein-AM as a cytosolic fluorophore. Calcein-AM has been used as a cytosolic fluorophore in mitochondrial permeability studies to image pore transition.