However, studies show that EGF is likely to induce tumor cell invasion in breast cancer (Klijn et al., 1992; Chrysogelos and Dickson, 1994; Hardy et al., 2010), where the overexpression of EGFR is connected with the loss of estrogen receptor and poor prognosis (Chrysogelos and Dickson, 1994). Here, ESR1 is linked to breast cancer.