1. M. J. Hart, W. Roscoe, G. Bollag, Onyx Pharmaceuticals, 3031 Research Drive, Richmond, CA 94806, USA.
2. X. Jiang, T. Kozasa, W. D. Singer, A. G. Gilman, P. C. Sternweis, Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75235–9041, USA.