A major research activity is managing the Brigham and Women痴 Hospital breast tumor frozen tissue bank. Since its establishment 4 years ago, the breast tumor bank has become an extensively utilized and invaluable tissue resource to scientists in our affiliated institutions for genomic research, gene validation, somatic mutation screening, and clinical outcomes research. My own research includes gene expression array analysis of human breast tumors to study cancer heterogeneity and taxonomy and to investigate the use of gene expression patterns to predict cancer stage or prognosis. I am particularly interested in the newly described basal-like breast tumor subset identified by expression array analysis. We have performed SNP array-based genome-wide loss-of-heterozygosity (LOH) analysis on the same tumor cohort and have found unique genomic alterations in certain subclasses of breast cancer. Future directions will include further LOH mapping of these unique regions and testing of candidate genes for mutations in the involved tumors. We will also seek to validate expression of specific gene markers for identification of the basal-like tumors by immunohistochemistry on tissue microarrays.