[1] Harvard Univ, Sch Med, Dana Farber Canc Inst, Boston, MA 02115 USA
[2] Harvard Univ, Sch Med, Dept Genet, Boston, MA 02115 USA
[3] Life Technol Inc, Rockville, MD 20850 USA
[4] Massachusetts Gen Hosp, Ctr Canc, Mol Oncol Lab, Charlestown, MA 02129 USA