1. IBM Computational Biology Center, Yorktown Heights, NY, 10598, USA.
2. European Bioinformatics Institute (EMBL-EBI), Welcome Trust Genome Campus, Cambridge CB10 1SD, UK.
3. European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Meyerhofstrasse 1, D-69117 Heidelberg, Germany.
4. Department of Mechanical Engineering, National Technical University of Athens, Heroon Polytechniou 9, 15780 Zografou, Athens, Greece.
5. Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA.
6. Department of Biological Engineering, MIT, Cambridge, MA 02139, USA.