ESR1 and breast cancer: Among the genes significantly associated with ER status, we identified known breast cancer related genes such as Microtubule Associated Protein Tau (MAPT), whose expression is highly associated with low sensitivity to taxanes that are important drugs for breast cancer treatment [36], and Macrophage migration inhibitory factor (MIF), a pro-inflammatory cytokine whose blockade reduces the aggressiveness of invasive breast cancer [37].