2010 TRI/PRINCETON CONFERENCE 125 (4) E. K. Nishimura, S. R. Granter, and D. E Fisher, Mechanisms of hair graying: Incomplete melanocyte stem cell maintenance in the niche, Science, 307, 720–724 (2005). (5) J. M. Wood, H. Decker, H. Hartmann, B. Chavan, H. Rokos, J. D. Spencer, S. Hasse, M J. Thornton, M. Shalbaf, R. Paus, and K. U. Schallreuter, Senile hair graying: H2O2-mediated oxidative stress affects human hair color by blunting methionine sulfoxide repair, FASEB J., 23(7), 2065–2075 (2009). (6) E. K. Nishimura, S. A. Jordan, H. Oshima, H. Yoshida, M. Osawa, M. Moriyama, I. J. Jackson, Y. Barrandon, Y. Miyachi, and S. Nishikawa, Dominant role of the niche in melanocyte stem-cell fate determination, Nature, 416, 854–860, (2002). (7) N. V. Botchkareva, M. Khlgatian, B. J. Longley, V. A. Botchkarev, and B. A. Gilchrest, SCF/c-kit signaling is required for cyclic regeneration of the hair pigmentation unit, FASEB J., 15(3), 654–658 (2001). (8) E. M. Peters, M. Maurer, V. A. Botchkarev, K. Jensen, P. Welker, G. A. Scott, and R. Paus, Kit is expressed by epithelial cells in vivo, J Invest. Dermatol., 121(5), 976–984 (2003). (9) D. J. Tobin, Aging of the hair follicle pigmentation system, Int. J. Trichology, 1(2), 83–93 (2009). (10) E. M. Peters, S. Hendrix, G. Gölz, B. F. Klapp, P. C. Arck, and R. Paus, Nerve growth factor and its precursor differentially regulate hair cycle progression in mice, J. Histochem. Cytochem., 54(3), 275–288 (2006). (11) E. M. Peters, S. Liotiri, E. Bodó, E. Hagen, T. Bíró, P. C. Arck, and R. Paus, Probing the effects of stress mediators on the human hair follicle: Substance P holds central position, Am. J. Pathol., 171(6), 1872– 1886 (2007). (12) E. M. Peters, C. Liezmann, K. Spatz, M. Daniltchenko, J. Kruse, B. F. Klapp, D. Imfeld, and R. Gräub, Profi lling mRNA of the graying human hair follicle constitutes a promising state of the art tool to assess the aging process and stress defence (in preparation).