1. H. W. Chang, M. Aoki, P. K. Vogt, Department of Molecular and Experimental Medicine, Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
2. D. A. Fruman and L. C. Cantley, Division of Signal Transduction, Beth Israel Deaconess Medical Center, Building HIM-1007, 330 Brookline Avenue, Boston, MA 02215, USA.
3. K. R. Auger and T. M. Roberts, Dana-Farber Cancer Institute, Mayer Building Room 854, 44 Binney Street, Boston, MA 02115, USA.
4. A. Bellacosa and P. N. Tsichlis, Fox Chase Cancer Center, 7701 Burholme Avenue, Philadelphia, PA 19111, USA.