1. Swiss Institute for Experimental Cancer Research (ISREC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Epalinges, Switzerland;
2. Ludwig Institute for Cancer Research, Lausanne Branch, University of Lausanne, Epalinges, Switzerland; and
3. Department of Molecular Embryology, Max-Planck Institute of Immunology, Freiburg, Germany