1. Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 01238, USA.
2. Stem Cell Program and Division of Hematology/Oncology, Boston Children’s Hospital and Dana-Farber Cancer Institute, Howard Hughes Medical Institute, Harvard Stem Cell Institute, Harvard Medical School, Boston, MA 02115, USA.
3. Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA.
4. Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
5. Department of Biology, McGill University, Montréal, Québec H3A 1B1, Canada.
6. Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA.
7. Department of Genome Regulation, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany.
8. Human Biology Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
9. Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
10. Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.