1. Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas; Dallas Texas 75390-9050
2. Department of Biophysics; University of Texas Southwestern Medical Center at Dallas; Dallas Texas 75390-9050
3. Department of Biochemistry; University of Texas Southwestern Medical Center at Dallas; Dallas Texas 75390-9050
4. Institute for Cancer Research; 333 Cottman Avenue Philadelphia 19111 Pennsylvania Fox Chase Cancer Center
5. Genome Center, University of California; 451 Health Sciences Drive Davis 95616 California