1. Max Planck Institute for Experimental Endocrinology (H.H., M.K.M., S.I., J.M., K.B.), D-30625 Hannover, Germany
2. Institute of Molecular Biotechnology (H.H.), D-07745 Jena, Germany
3. Department of Internal Medicine, Erasmus Medical Center (E.C.H.F., T.J.V.), 3015 GE Rotterdam, The Netherlands