For over three decades, the goal of this program project grant has been to develop and apply radioactive tracer techniques that provide detailed knowledge of regional biochemistry in living human beings under normal conditions and when affected by diseases, including cancer. Specifically, our present proposal concerns that development, validation and use of radioactive tracers that allow in vivo localization of sigma, opioid, somatostatin and bombesin recognition sites known to be of fundamental importance in oncology. These recognition sites are expressed in a variety of neural and non-neural tumors, and play key roles in the regulation of cell growth and proliferation. Validated biomarkers for in vivo localization of such tumors by positrons emission tomography (PET) and single photon emission computed tomography (SPECT) would aid in cancer diagnosis and management. Our program requires multidisciplinary participation of chemists, biologists, physicists and physicians; and is multidepartmental, involving the Johns Hopkins School of Public Health and the School of Medicine. As a member of a well- coordinated group of scientists, each with special expertise, the investigators will be able to make research advances that are not feasible on an individual basis. The program provides a continuing focus for investigators to obtain new knowledge of in vitro and in vivo biochemistry relevant to cancer through the design, evaluation and application of novel radiotracer techniques. Our translational research will provide useful new tools and 'basic' knowledge that should lead to advances in medical imaging of benefit in the oncology arena.