1 Department of Dermatology, Center for Molecular Medicine Cologne, Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases, SFB 829 "Molecular Mechanisms Regulating Skin Homeostasis," University of Cologne, Cologne, Germany. Electronic address: carien.niessen@uni-koeln.de.
2 Department of Dermatology, Center for Molecular Medicine Cologne, Cologne Excellence Cluster on Cellular Stress Responses in Aging-associated Diseases, SFB 829 "Molecular Mechanisms Regulating Skin Homeostasis," University of Cologne, Cologne, Germany.