[1] MIDDLESEX HOSP,SCH MED,ACAD DEPT GENITOURINARY MED,LONDON WIN,ENGLAND
[2] CHESTER BEATTY LABS,INST CANC RES,LONDON SW3 6JB,ENGLAND
[3] UNIV PENN,DEPT BIOL,PHILADELPHIA,PA 19104
[4] CTR DIS CONTROL,IMMUNOL BRANCH,ATLANTA,GA 30333
[5] UNIV NAPLES,INST BIOCHEM SCI,I-80131 NAPLES,ITALY
[6] COLUMBIA UNIV,HOWARD HUGHES MED INST,NEW YORK,NY 10032
[7] COLUMBIA UNIV,DEPT BIOCHEM & MOLEC BIOPHYS,NEW YORK,NY 10032