Three Vanderbilt University Medical Center faculty members were invited symposium speakers at the 9th International Congress of Toxicology, held this week in Brisbane Australia. F. Peter Guengerich, Ph.D., professor of Biochemistry and director of the Center in Molecular Toxicology, presented “Expressed P450s in toxicology assays.” Lawrence J. Marnett, Ph.D., Mary Geddes Stahlman Professor of Cancer Research and Biochemistry, presented “Oxy radicals, lipid peroxidation, and DNA damage.” Jennifer A. Pietenpol, Ph.D., associate professor of Biochemistry, presented “Cell cycle checkpoint signaling: cell cycle arrest versus apoptosis.”