[1] HARVARD UNIV,SCH MED,DEPT BIOL CHEM & MOLEC PHARMACOL,BOSTON,MA 02115
[2] HARVARD UNIV,SCH MED,DANA FARBER CANC INST,TUMOR VIRUS GENET LAB,BOSTON,MA 02115
[3] HARVARD UNIV,SCH MED,DEPT MICROBIOL & MOLEC GENET,BOSTON,MA 02115
[4] UNIV MASSACHUSETTS,SCH MED,DEPT PHARMACOL,WORCESTER,MA 01655