[1] Dana Farber Canc Inst, Dept Canc Biol, CCSB, Boston, MA 02115 USA
[2] Harvard Univ, Sch Med, Dept Genet, Boston, MA USA
[3] Howard Hughes Med Inst, Boston, MA 02115 USA
[4] Harvard Univ, Div Engn & Appl Sci, Appl Phys Program, Grad Sch Arts & Sci, Cambridge, MA 02138 USA
[5] Harvard Univ, Sch Med, Dept Biol Chem & Mol Pharmacol, Boston, MA 02115 USA