1. Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015 Lausanne, Switzerland
2. Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), D-69117 Heidelberg, Germany
3. Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany