1. J. D. Minna is in the Departments of Internal Medicine and Pharmacology and A. F. Gazdar is in the Department of Pathology, Hamon Center for Therapeutic Oncology Research, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
2. S. R. Sprang is in the Howard Hughes Medical Institute, Department of Biochemistry, and J. Herz is in the Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.