1. From The Hospital for Special Surgery—Philip D. Wilson Research Foundation, affiliated with The New York Hospital—Cornell University Medical College, and the Department of Pathology, Cornell University Medical College, New York, 10021, the Division of Immunology, Sloan-Kettering Institute for Cancer Research, New York 10021, and the Viral Carcinogenesis Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20014