1. Faculty of Arts and Sciences, Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA.
2. School of Computer Science and Engineering, The Hebrew University, Jerusalem 91904, Israel.
3. Department of Molecular Genetics and Biotechnology, Faculty of Medicine, The Hebrew University, Jerusalem 91120, Israel.
4. Department of Biological Chemistry and Molecular Pharmacology, Harvard University, 240 Longwood Avenue, Boston, MA 02115, USA.