1. Institute for Stem Cell Biology and Regenerative Medicine, Stanford Cancer Center, and Ludwig Center at Stanford, Stanford, CA 94305, USA.
2. Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA.
3. Department of Internal Medicine, Division of Hematology, Stanford University, Palo Alto, CA 94304, USA.
4. Division of Oncology, Stanford University, Palo Alto, CA 94304, USA.
5. Department of Radiology, Stanford University, Palo Alto, CA 94304, USA.
6. Departments of Pathology and Clinical Laboratories and Human Oncology and Pathogenesis Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.