1. M. B. Yaffe, Division of Signal Transduction, Department of Medicine and Department of Surgery, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.
2. M. Schutkowski, J.-U. Rahfeld, G. Fischer, Max-Planck Research Unit on Enzymology of Protein Folding, Kurth-Mothes Strasse 3, 06120 Halle, Germany.
3. M. Shen and X. Z. Zhou, Cancer Biology Program, Division of Hematology and Oncology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.
4. P. T. Stukenberg and M. W. Kirschner, Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
5. J. Xu, Division of Signal Transduction, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.