EGFR and breast cancer: In addition, mERα homodimer can physically interact to the p85 subunit of the PI3K kinase, to the SH2 (Src Homology 2) domain of the c-Src kinase, or even activate membrane receptors with tyrosine kinase activity, such as Epidermal Growth Factor Receptor (EGFR) which stimulates the ERK (extracellular-signal-regulated kinase) or PI3K signaling pathways, increasing cell proliferation, survival, and migration of breast cancer cells (25, 26).