1. Department of Tissue Morphogenesis, Max Planck Institute for Molecular Biomedicine, Muenster, Germany;
2. Faculty of Medicine, University of Münster, Muenster, Germany;
3. Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Muenster, Germany;
4. Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Muenster, Germany; and
5. Mass Spectrometry Unit and
6. Flow Cytometry Unit, Max Planck Institute for Molecular Biomedicine, Muenster, Germany