2 Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
3 Department of Genetics and Department of Bioinformatics and Computational Biology, The University of Texas, MD Anderson Cancer Center, Houston, Texas, USA.
4 Department of Mathematics, University of California, Berkeley, California, USA.
5 European Bioinformatics Institute, European Molecular Biology Laboratory, Cambridge, UK.
6 Department of Chemistry, University of Illinois, Urbana, Illinois, USA.