[1] HARVARD UNIV, SCH MED, DANA FARBER CANC INST, TUMOR VIRUS GENET LAB, BOSTON, MA 02115 USA
[2] HARVARD UNIV, SCH MED, DANA FARBER CANC INST, MOLEC BIOL LAB, BOSTON, MA 02115 USA
[3] HARVARD UNIV, SCH MED, DEPT MICROBIOL & MOLEC GENET, BOSTON, MA 02115 USA
[4] HARVARD UNIV, SCH MED, DEPT BIOL CHEM, BOSTON, MA 02115 USA
[5] HARVARD UNIV, SCH MED, COMM CELL BIOL & DEV BIOL, BOSTON, MA 02115 USA