1. European Molecular Biology Laboratory, 69117 Heidelberg, Germany
2. Computational Biology, Mines ParisTech, 75006 Paris, Cedex 5, France
3. Research Center, Curie Institute, 75005 Paris, Cedex 5, France
4. Unit 900, Institut National de la Santé et de la Recherche Médicale, 75005 Paris, Cedex 5, France