ESR1 and breast neoplasm: In addition, we observed changes in the expression of specific genes, including significant reductions in the expression of Rb1, Esr1, and Pgr, and increases in the expression of Erbb2, Egfr, and the genes encoding keratins 5, 6, and 17 (Figure 1B), as they are in human basal-like breast tumors (Cancer Genome Atlas 2012).