Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany.|Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany.|Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany.|Institute for Theoretical Biology, Humboldt University of Berlin, Berlin, Germany.|Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany.