1. Department of Pharmacy, Johannes Gutenberg-University, Staudingerweg 5, D-55099 Mainz, Germany, Department of Single Cell and Single Molecule Techniques, Institute of Molecular Biotechnology, Beutenbergstraβe 11, D-07745 Jena, Germany, ProQinase GmbH, Breisacherstrasse 117, D-79106 Freiburg, Germany, Department of Pharmacy, Philipps-University, Marbacherweg 6, D-35032 Marburg, Germany, and Department of Organic Chemistry, Johannes Gutenberg-University, Duesbergweg 10-14, D-55099 Mainz, Germany