1. National Toxicology Program, Research Triangle Park, North Carolina, USA
2. Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut, USA
3. Experimental Pathology Laboratories, Inc., Northwest, Seattle, Washington, USA
4. Amgen Inc., South San Francisco, California, USA
5. Covance Laboratories, Madison, Wisconsin, USA
6. U.S. Food and Drug Administration, Silver Spring, Maryland, USA
7. Experimental Pathology Laboratories, Inc., Durham, North Carolina, USA