The mission of the JBL Center is to apply its considerable expertise in signal transduction, molecular toxicology, and molecular stress responses as well as that of affiliated units to enhance our understanding of the hazards of exposure of human populations to ionizing radiation and other toxicants, and how these hazards may be controlled or prevented. An important focus is to improve our understanding of the molecular mechanisms involved in the cellular response to genotoxic agents including agents with therapeutic potential as well as environmental toxicants. In the case of accidental or intentional radiation exposures in the environment, the Center has an active radiation countermeasures program and cooperates with others at the University and elsewhere in formulating effective strategies to respond to such incidents.