application) This core will function as the principal laboratory core for the program project. Components of the core include 1) an animal and histology core, and 2) an animal and molecular biology core. The animal and histology part of the core will maintain breeding colonies of wild type and mutant mice, perform UUO procedures in rats and mice, and perform histology, interstitial volume measurements, detection of monocytes and macrophages, in situ hybridization, assays for apoptosis, and measurements of renal function. The animal and molecular biology portion of the core will be responsible for cell culture, generation of promoter-reporter and gene targeting constructs, and production of transgenic and knockout mice.