1. I. Mellon, D. K. Rajpal, G. N. Champe, Department of Pathology, Program in Toxicology, Markey Cancer Center, University of Kentucky, Lexington, KY 40536, USA.
2. M. Koi, Laboratory of Molecular Carcinogenesis, National Institute of Environmental Health Sciences, Post Office Box 12233, Research Triangle Park, NC 27706, USA.
3. C. R. Boland, Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0688, USA.