This T32 Training Grant has focused successfully over the past 25 years on providing a dynamic research training environment for pathologists, other physician-scientists and basic scientists working in molecular pathology. Over the past two 5-year funding periods, trainees have published a considerable number of papers, including in high quality journals, and have found faculty positions in prestigious medical schools. The present, proposed configuration of the grant features 20 Harvard Medical School faculty centered in the Molecular Pathology Unit and Cancer Center. This interactive, overlapping community of scientists and physician-scientists is organized into thematic programs in cancer genetics;animal models of cancer;signal transduction and oncogenesis;mechanisms of gene regulation;cell cycle control;hematopoiesis and stem cells;and immunobiology. The present proposal also incorporates important changes: a further focus toward cancer biology;a shift in faculty, reflecting participation during the prior funding period and scientific direction;an administrative reorganization to broaden scientific and mentoring input;and a request to increase from 5 to 7 training positions. As in previous cycles, the trainees will be selected from a competitive pool of MD, MD-PhD and PhD applicants on the basis of prior academic and research achievements and evidence of a strong commitment to a career in science. The period of training will be two or three years for each successful applicant. An active minority outreach approach ensures access to the training program by underrepresented minorities, as evidenced by a successful record (3 of 12 trainees in the past funding period were underrepresented minorities). In summary, the proposed T32 program renewal capitalizes on a highly interactive, experienced and focused faculty;a distinguished record of training productive physicians and scientists, including minorities;state-of-the-art facilities and educational resources;and exposure of the trainees to basic and translational aspects of cancer biology.