This project was initiated to study the mechanism of chemical carcinogenesis by employing the technique of quantitative two-dimensional electrophoresis of total cellular proteins. The technique of two-dimensional get electrophoresis allows the simultaneous separation of hundreds of polypeptides in a single polyacrylamide gel. We have acquired, and are further developing, a computer-based system to automatically analyze autoradiograms produced from these gels. This system automatically finds and measures the amount of radioactivity in any polypeptide resolved by these electrophoretograms. Other semi-automatic programs match together the spot patterns found in different gels and can flag those spots which are missing or vary significantly in one electrophoretogram or the other. Still other programs link together a series of gels which may constitute an experiment and allow the investigator to quantitatively follow the synthesis of almost any protein through that experiment or through a series of related experiments.