1. Laboratory of Comparative Genomics, University of Illinois, Urbana, Illinois 61801
2. Department of Veterinary Pathobiology, University of Illinois, Urbana, Illinois 61801
3. Laboratory of Molecular Genetics, Department of Animal Sciences, University of Illinois, Urbana, Illinois 61801
4. Department of Pharmacology and Oncology, Duke University Medical Center, Durham, North Carolina 27710