1. Institute of Clinical Chemistry, University Medical Center Göttingen , Göttingen , Germany
2. Institute of Clinical Chemistry and Laboratory Medicine, University Medicine Oldenburg , Oldenburg , Germany
3. Institute of Clinical Chemistry and Laboratory Medicine, University Medicine Greifswald , Greifswald , Germany
4. Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center Hamburg-Eppendorf , Hamburg , Germany
5. Division Vascular Signaling and Cancer, German Cancer Research Center , Heidelberg , Germany