1. Retina Research Laboratory, Massachusetts Eye and Ear InfirmaryHarvard Medical School 325 Cambridge Street Boston Massachusetts USA
2. Department of Vitreoretinal SurgeryCenter for OphthalmologyUniversity of Cologne Joseph Stelzmann Str. 9 50931 Köln Germany
3. Center for Molecular Medicine (ZMMK)University of Cologne 50931 Köln Germany
4. Department of Adult OncologyDana-Farber Cancer InstituteHarvard Medical School Boston Massachusetts USA