[1] St Jude Childrens Res Hosp, Dept Biochem, Memphis, TN 38105 USA
[2] Harvard Univ, Brigham & Womens Hosp, Sch Med, Dept Pathol, Boston, MA 02115 USA
[3] Harvard Univ, Sch Med, Div Hematol & Oncol, Boston, MA 02115 USA
[4] Emory Univ, Dept Pathol, Atlanta, GA 30322 USA
[5] NYU, Sch Med, Dept Pathol, New York, NY 10016 USA
[6] Univ Tokyo, Inst Med Sci, Tokyo 108, Japan
[7] Howard Hughes Med Inst, Coconut Grove, FL 33133 USA