1. a Max Planck Institute of Molecular Cell Biology and Genetics , Dresden, Germany
2. e Division of Biology , California Institute of Technology , Pasadena, California, USA
3. b Max Planck Institute for the Physics of Complex Systems , Dresden, Germany
4. f Department of Systems Biology , Harvard University , Boston, Massachusetts, USA
5. c Max Planck Institute of Molecular Cell Biology and Genetics , Dresden, Germany E-mail:
6. d Max Planck Institute for the Physics of Complex Systems , Dresden, Germany E-mail: