[1] Harvard Univ, Sch Med, Lab Allergy & Immunol, Boston, MA 02215 USA
[2] Harvard Univ, Sch Med, Beth Israel Deaconess Med Ctr, Div Signal Transduct, Boston, MA 02215 USA
[3] Harvard Univ, Sch Med, Dept Pathol, Boston, MA 02215 USA
[4] Harvard Univ, Sch Med, Dept Cell Biol, Boston, MA 02215 USA
[5] Kansai Med Univ, Dept Mol Genet, Moriguchi, Osaka 570, Japan