The goal of the experimental animal core is to provide relevant mouse and rat models for studying the development of tumors in the colon and the apoptotic pathway. These systems will provide models for evaluating nutritional and other extracellular factors such as hormones or bile acids that may affect the apoptotic pathway and for evaluating the effects of potential chemopreventive agents. Included in these models are mice that have defective genes, p53, BCl2, and APC which have been shown in both human and mouse colon tumors to be involved in the oncogenesis of these tumors. These models allow for a more targeted approach for identification of molecular targets for chemoprevention. The specific aims of the core are: 1) to provide relevant murine models to study colon oncogenesis and the apoptotic pathway; 2) to provide treatments, carcinogens or dietary, that promote tumor development in each appropriate model; 3) to administer chemopreventive agents and 4) to provide fresh tissues from the animal study protocols to each project. The experimental animal core provides a means in which animals needed for studies by four different projects can be shared and the results of the studies are combinative. The advantages to having a experimental animal core are: less animals are needed than if each project performed the animal studies by themselves; there is uniformity and quality control in carrying out the study protocols across each project; data generated from each study is comparable given that the information is generated from the same sources with common controls and, the core allows us to examine multiple rodent models of colon cancer that would otherwise be unaffordable. In this program, both normal and neoplastic colonic tissues will be analyzed.