1. Department of Chemical Immunology, The Weizmann Institute of Science, Rehovot, Israel
2. Department of Neurosurgery, Ichilov Hospital, Tel Aviv Medical Center, Tel Aviv, Israel
3. Department of Neurobiology, The Weizmann Institute of Science, Rehovot, Israel
4. Protein Chemistry Laboratory, Imperial Cancer Research Fund, Lincoln’s Inn Fields, London WC2A 3PX, U.K.
5. Department of Molecular Biology, Genentech, Inc., 460 Point San Bruno Boulevard, South San Francisco, California 94080, U.S.A.