Using two independently-derived ER positive MCF-7 human breast cancer cell models of acquired TAMr developed in our laboratory [9], an Affymetrix® microarray study showed that 131 genes were upregulated and 156 were downregulated by at least 3-fold, in TAMr MCF-7 cells relative to isogenic control cells [10]. This evidence concerns the gene ESR1 and breast carcinoma.