1. Department of Biology, Institute of Cell Biology, Swiss Federal Institute of Technology (ETH) Zurich, CH-8093 Zurich, Switzerland
2. Molecular Biology Laboratory, Department of Pathology, University Hospital of Zurich, CH-8091 Zurich, Switzerland
3. Laboratory of Stem Cell Dynamics, School of Life Sciences, Ecole Polytechnique Féderale de Lausanne and Lausanne University Hospital, CH-1015 Lausanne, Switzerland
4. UMR144, Centre National de la Recherche Scientifique, Institut Curie, 75248 Paris, Cedex 05, France
5. Department of Cell Biology and Genetics, Erasmus University Medical Center, 3000DR Rotterdam, Netherlands
6. Swiss Institute for Experimental Cancer Research, 1066 Epalinges, Switzerland