1. Apoptosis and Proliferation Control Laboratory, Cancer Research UK, London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3PX, United Kingdom
2. Institute for Signaling, Developmental Biology and Cancer, Centre National de la Recherche Scientifique Unité Mixte de Recherche 6543, Parc Valrose, 06108 Nice Cedex 2, France
3. Genome Biology, Gene Expression Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
4. Max-Planck-Institut für Immunbiologie, Stübeweg 51, 79108 Freiburg im Breisgau, Germany
5. MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, United Kingdom