DESCRIPTION: (Applicant's Description) The purpose of the Pathology Shared Resource is to provide high quality, economical, and time pathology- related services to SACI investigators. Most of the SACI investigators using this core are not pathologists and have limited pathology training. By interacting with the core facility, SACI members are educated in how histologic approaches in experiment designed can enhanced their research. In particular, the in situ analysis of cancer-related molecules by immunohistochemistry has provided many insights. The availability of appropriate tissue/tumor bank specimens to generate and test hypotheses in vivo in human tissue has also been very helpful. Experienced pathologist are essential to interpret many of the procedures performed in the core and to efficiently perform the wide range of core procedures/services, The cost of purchasing and maintaining the equipment and supplies necessary to provide these services is high and would be expensive and cost-prohibitive to duplicate. With SACI, institutional, and departmental support, the Pathology Shared Resource has evolved into a well-equipped, stable and high-quality facility. Utilization of this efficient and centralized resource has provided significant scientific and financial benefits to many SACI investigators. The specific procedures/services provided by the Pathology Shared Resource include: Routine histology/histochemistry (e.g., preparing paraffin blocks and H&E slides); Special histochemistry (such as special stains); Immunohistochemistry (with fluorescent and enzyme detection systems); Photomicroscopy (new service); Fluorescent microscopy (new service); Microdissection (existing manual technology soon to be replaced with laser capture technology); Tumor banking (5,200 frozen tumors of many types, 708 archival prostate cancers with follow-up); Consultation/collaboration with experience technologists and pathologists; Confocal laser microscopy (planned new service).