The ability to use microarray-based gene profiling approaches to define global patterns of gene expression during embryonic development, in response to specific hormonal and physiological stimuli, and in pathological and disease states, in genetically modified animals, and pharmacogenomics represents an important technological advance. This technology requires both expensive and sophisticated instrumentation and specific expertise in the form of array fabrication, bioinformatics and statistical support. Recognizing the importance of this technology in biological research, two years ago Northwestern University created the Northwestern University Microarray Core (NUMAC) to provide such a resource for its investigators. Currently, NUMAC is providing a wide range of services to its users including consultation in experimental design and analysis, performing hybridizations for custom and prefabricated arrays (Affymetrix GeneChips), and printing custom arrays. The NUMAC labeling and processing service for GeneChips has been offered in conjunction with Children's Memorial Hospital Institute for Education and Research (CMIER). The number of NUMAC users has increased significantly and this has caused a long turnaround time for processing of the samples at CMIER. This problem is going to exacerbate as both NU campuses (Evanston, Chicago) employ more GeneChips related projects. The Affymetrix GeneChips can only be processed by the Affymetrix system and the goal of this application is to request funds to purchase an Affymetrix GCS Instrument to enhance our existing capabilities for the GeneChip processing in a timely manner with a higher quality.