1. Institute for Tumor Biology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany, Institute of Clinical Chemistry, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany, Department of Plant Biochemistry and Biotechnology, Westphalian Wilhelm’s-University Münster, Hindenburgplatz 55, 48143 Münster, Germany, and Institute of Medical Physics and Biophysics, Westphalian Wilhelm’s-University Münster, Robert-Koch Str. 31, D-48149 Münster, Germany