1. University of Texas Southwestern, Dallas, Texas, United States
2. University of Chicago, Chicago, Illinois, United States
3. University Hospital Ulm, Ulm, Germany
4. St Jude Children's Research Hospital, Memphis, Tennessee, United States
5. Children's Hospital Los Angeles, Los Angeles, California, United States
6. Lund University, Sweden
7. Dana-Farber Cancer Institute, Boston, Massachusetts, United States
8. Johns Hopkins University, Baltimore, Maryland, United States