The demonstration of gene transfer, mRNA and protein expression and biological efficacy is critical to the successful development of gene transfer vectors and pharmacologic therapies. An Expression Core has been in operation at Johns Hopkins University since the beginning of the grant. This Core has considerable expertise in assaying for normal and defective function of CFTR by methods such as: 1. Functional assays such as patch clamping; 2. Evaluating gene transfer, mRNA expression, vector shedding and spread in animal and patients samples 3. Assaying for protein expression Work from this Core during the previous budget period was instrumental in the continued development of adeno-associated virus as an extremely promising therapeutic agent. The recent development of gene transfer technologies as potential therapies have increased considerably the demand for the services of our Expression Core. Along these lines, the Core has developed considerable expertise in primate experiments in Rhesus monkeys and more recently in chimpanzees. The Expression Core functions as both a research and development Core, and in addition, provides support for the projects within this Gene Therapy Center. RELEVANCE (See instructions):