1. From the Division of Experimental Ophthalmology, the Centre for Ophthalmology, Tübingen, Germany;
2. the Department of Human Morphology and Developmental Biology, Semmelweis University, Budapest, Hungary;
3. the Department of Cell Biology, SUNY Downstate Medical Center, Brooklyn, New York; and
4. the NMI Natural and Medical Sciences Institute, the University of Tübingen, Rütlingen, Germany.