- The vesicular monoamine transporter 2 (VMAT2) is expressed by normal and tumor cutaneous mast cells and Langerhans cells of the skin but is absent from Langerhans cell histiocytosis. Anlauf, M., Schafer, M.K., Depboylu, C., Hartschuh, W., Eiden, L.E., Kloppel, G., Weihe, E. J. Histochem. Cytochem. (2004)