1. University of Colorado School of Medicine, Aurora, Colorado.
2. University Health Network, University of Toronto, Toronto, Canada.
3. Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
4. The Mayo Clinic, Rochester, Minnesota.
5. Johns Hopkins University School of Medicine, Baltimore, Maryland.
6. Boston Medical Center, Boston, Massachusetts.
7. Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
8. The Mayo Clinic, Jacksonville, Florida
9. The University of Siena, Siena, Italy.
10. Institute Gustave Roussy and University Paris Sud, Villejuif, France.
11. Oregon Health and Science University, Portland, Oregon.
12. University of Texas M.D. Anderson Cancer Center, Houston, Texas.
13. Duke University School of Medicine, Durham, North Carolina.
14. University of Cincinnati Medical Center, Cincinnati, Ohio.
15. MedStar Washington Hospital Center, Washington, DC.