1. Departments of Surgery and Physiology, University of California, San Francisco, San Francisco, CA 94143
2. Department of Dermatology, Interdisciplinary Center for Clinical Research, and the Ludwig Boltzmann Institute for Cell Biology and Immunobiology of the Skin, University of Münster, 48149 Münster, Germany
3. INSERM U 36 College de France Paris, 75005 Paris, France