1. Epigenetics Institute, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
2. Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
3. European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg, Germany
4. Collaboration for Joint PhD Degree between EMBL and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
5. Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
6. Center for Proteomics and Metabolomics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA