1. Institute of Pathology, Department of Applied Tumor Biology Faculty of Medicine Ruprecht-Karls-University Heidelberg Im Neuenheimer Feld 224 69120 Heidelberg Germany
2. Roy & Diana Vagelos Laboratories Department of Chemistry University of Pennsylvania Philadelphia Pennsylvania 19104-6323 USA
3. Institute of Physiological Chemistry, Faculty of Veterinary Medicine Ludwig-Maximilians-University Munich Veterinaerstr. 13 80539 Munich Germany
4. Centro de Investigaciones Biológicas CSIC Ramiro de Maeztu, 9 28040 Madrid Spain
5. Institute for Computational Molecular Science Temple University Philadelphia Pennsylvania 19122 USA