1. Institute of Cell Biochemistry, Hannover Medical School, Hannover, Germany
2. Max Planck Research Group of Gene Expression and Signaling, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
3. Bioanalytical Mass Spectrometry Research Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
4. University Medical Center Göttingen, Bioanalytics, Institute for Clinical Chemistry, Göttingen, Germany