1. Vincent Center for Reproductive Biology, Department of Obstetrics and Gynecology, Massachusetts General Hospital/Harvard Medical School (Y.T., J.C., G.I.P., J.K.P., J.L.T.), Boston, Massachusetts 02114
2. Department of Environmental Health, Boston University Schools of Medicine and Public Health (J.J.S., D.H.S.), Boston, Massachusetts 02118
3. Laboratory of Signal Transduction, Memorial Sloan-Kettering Cancer Center (R.N.K.), New York, New York 10021
4. Department of Cell Biology, Harvard Medical School (J.Y.), Boston, Massachusetts 02115
5. Section of Immunobiology, Yale University School of Medicine (R.A.F.), New Haven, Connecticut 06510
6. Departments of Pathology and Medicine, Dana-Farber Cancer Institute/Harvard Medical School (S.J.K.), Boston, Massachusetts 02115