[1] Univ Massachusetts, Sch Med, Dept Mol Pharmacol & Biochem, Program Syst Biol, Worcester, MA 01605 USA
[2] CNAG, Genome Biol Grp, Barcelona 080828, Spain
[3] CRG, Gene Regulat Stem Cells & Canc Program, Barcelona 08003, Spain
[4] MIT, Inst Med Engn & Sci, Cambridge, MA 02139 USA
[5] MIT, Dept Phys, Cambridge, MA 02139 USA