1. Novartis Institutes for Biomedical Research, CH-4000 Basel, Switzerland
2. Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford OX1 3QX, England, UK
3. Friedrich-Miescher Institute for Biomedical Research, CH-4000 Basel, Switzerland
4. Department of Biomedicine, University of Basel, CH-4058 Basel, Switzerland
5. Novartis Institutes for Biomedical Research, Cambridge, MA 02139
6. Department of Laboratory Medicine, Karolinska Institutet, SE-141 86 Huddinge, Sweden