1. Howard Hughes Medical Institute and Boyer Center for Molecular Medicine, Stanford University School of Medicine, Palo Alto, California
2. Section of Neurosurgery, Stanford University School of Medicine, Palo Alto, California
3. Department of Cell Biology, Stanford University School of Medicine, Palo Alto, California
4. Yale University School of Medicine, New Haven, Connecticut; Department of Neurosurgery, Stanford University School of Medicine, Palo Alto, California
5. Departments of Medicine and Genetics, Stanford University School of Medicine, Palo Alto, California