Abstract: The present invention is a cell-based method of identifying a set of signal transduction proteins having an intracellular localization pattern responsive to toxic compounds. The method requires identifying and screening an initial set of signal transduction proteins against a set of toxic compounds, and determining changes in intracellular localization pattern of each of the proteins. Proteins whose changes in intracellular localization pattern are redundant are discarded from the initial set, and new proteins are added to provide a new set of proteins. I repeat the method steps with new sets of proteins until the set of proteins provides me at least 5 principal components with respect to the range of compounds marketed as small organic molecules.