Dr. Polyak has been at the forefront of studies employing genomic approaches for breast cancer. Her lab was the first to perform comprehensive molecular characterization of the tumor and determined that gene expression and epigenetic alterations occur in each cell type during tumor progression whereas clonally selected genetic changes are limited to tumor epithelial cells. Dr. Polyak’s lab was among the first to comprehensively characterize stem cells from normal breast tissue and breast carcinomas.