1. Picower Institute for Medical Research, Manhasset, New York 11030
2. Dana Farber Cancer Institute, Boston, Massachusetts 02115
3. Zycos, Cambridge, Massachusetts 02138
4. Eppley Cancer Institute, Omaha, Nebraska 68198
5. Picower Institute for Medical Research, Manhasset, New York 11030 and Department of Microbiology and Tropical Medicine, George Washington University, Washington, D.C. 20037