1. M. Sattler, H. Liang, D. Nettesheim, R. P. Meadows, J. E. Harlan, M. Eberstadt, H. S. Yoon, S. B. Shuker, S. W. Fesik, Pharmaceutical Discovery Division, Abbott Laboratories, Abbott Park, IL 60064, USA.
2. B. S. Chang, A. J. Minn, C. B. Thompson, Howard Hughes Medical Institute and Departments of Medicine, Molecular Genetics, and Cell Biology, University of Chicago, Chicago, IL 60637, USA.