1. Schering-Plough Research Institute, Lafayette, NJ 07848, USA
2. Merck Research Laboratories, West Point, PA 19486, USA
3. Albert Einstein College of Medicine, Bronx, NY 10461, USA
4. Vet Path Services Inc., Mason, OH 45040, USA
5. Pfizer, Inc., Groton, CT 06340, USA; 5Philip H. Long, Vet Path Services, Inc., Mason, OH 45040, USA
6. Bracco Research SA, Geneva, CH-1228, Switzerland
7. Genentech, Inc., South San Francisco, CA 94080, USA
8. Wyeth Research, Chazy, NY 12921, USA