The PDX/Biospecimen Core B provides part of the infrastructure support for the P01 Projects. It has been designed to meet the needs of these projects and serve as a stand-alone resource for collaborative efforts. The Core B will provide a well-organized and standardized system of specimen collection, storage, distribution and related clinical/research information dissemination. There will be consistency and quality assurance in the pathological analysis of tissue specimens. Specimens from our repository, our LuCaP prostate cancer PDXs and clinical specimens, particularly those from our rapid autopsy program (e.g. prostate cancer bone metastases) have been and will continue to be distributed to other prostate cancer investigators on a national and international basis. The Core B Specific Aims are: 1) Maintain and Distribute Patient-Derived Prostate Cancer Xenografts, 2) Collect and Distribute Clinical Biopecimens (i.e. tissues, including those from surgery and the rapid autopsy program, serum, plasma and urine), processing, quality control, storage, distribution and database entry, 3) Establish and Maintain Specimen Quality and Core B Service Efficiency Programs, 4) Provide Specialized Pathology and Laboratory Services, including production of tissue microarrays, interpretation of immunohistology by urologic pathologists, production of specimen derivatives and perform PSA immunoassays for research, 5) Administrative Program to obtain samples from minorities, prioritize the distribution of specimens, ensure patient confidentiality and compliance with IRB requirements, and continually improve quality control measures.