[1] JAPANESE FDN CANC RES,INST CANC,DEPT CELL BIOL,TOSHIMA KU,TOKYO 170,JAPAN
[2] TOHOKU UNIV,INST DEV AGING & CANC,DEPT MOL IMMUNOL,AOBA KU,SENDAI,MIYAGI 980,JAPAN
[3] UNIV TOKYO,INST MED SCI,DEPT HEMATOL ONCOL,MINATO KU,TOKYO 108,JAPAN
[4] KYOTO UNIV,INST VIRUS RES,DEPT VIRAL ONCOL,SAKYO KU,KYOTO 606,JAPAN