1. M. Dickens, J. S. Rogers, J. Cavanagh, R. J. Davis, Howard Hughes Medical Institute and Program in Molecular Medicine, Department of Biochemistry and Molecular Biology, University of Massachusetts Medical School, 373 Plantation Street, Worcester, MA 01605, USA.
2. A. Raitano, J. R. Halpern, C. L. Sawyers, Department of Medicine, University of California School of Medicine, Los Angeles, CA 90095, USA.
3. Z. Xia and M. E. Greenberg, Division of Neuroscience, Department of Neurology, Children's Hospital, and Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.