[1] Wellcome Trust Genome Campus, Wellcome Trust Sanger Inst, Cambridge CB10 1SA, England
[2] Spanish Natl Canc Res Ctr CNIO, Struct Biol & Biocomp Programme, Madrid, Spain
[3] RIKEN, Yokohama Inst, Om Sci Ctr, Kanagawa, Japan
[4] Cold Spring Harbor Lab, Cold Spring Harbor, NY 11724 USA
[5] Univ Pompeu Fabra, Ctr Genom Regulat, Barcelona, Catalonia, Spain