1. Radiation Biology and DNA Repair, Darmstadt University of Technology, 64287 Darmstadt, Germany
2. The Howard Hughes Medical Institute, Department of Molecular Genetics and Microbiology, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712
3. Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030
4. Centre National de la Recherche Scientifique Unité Mixte de Recherche 8200, Institut de Cancérologie Gustave-Roussy, Université Paris-Sud, F-94805 Villejuif, France
5. Genome Damage and Stability Centre, University of Sussex, Brighton BN1 9RQ, England, UK