1. Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
2. Medical Scientist Training Program, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
3. Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
4. Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85277, USA.
5. Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
6. Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
7. McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.