Christopher J. Corton currently works at the Office of Research and Development, United States Environmental Protection Agency. His lab has recently developed gene expression biomarkers that can be used to identify transcription factor (TF) modulation after chemical exposure in the tissues of animals or cells in culture. These biomarkers can be used to identify 1) the chemical mode of action, 2) known or novel chemicals that activate or suppress the TF, 3) the frequency of the responses across the chemicals, 4) genes that when modulated activate or suppress the TF in the absence of chemical exposure, and 5) interactions between the TFs.