1. Department of Cell Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
2. Center for Biochemistry, University Hospital Cologne, University of Cologne, Cologne, Germany
3. Institute of Biological Information Processing, Molecular and Cellular Physiology, Research Center Juelich, Juelich, Germany
4. Department of Pediatrics, University Hospital Cologne, University of Cologne, Cologne, Germany