1. Department of Environmental Medicine, NIEHS Center, and Kaplan Comprehensive Cancer Center, New York University School of Medicine, New York, New York 10016
2. Université Montpellier II, 34095 Montpellier Cedex 05, France
3. Center for Cancer Research, National Institutes of Health, Bethesda, Maryland 20892
4. Department of Gastrointestinal Medical Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030