In addition, relevant studies in lung and breast cancer have shown that the activation of the Src/ERK1/2 pathway by GPER involves the activation of mitogen-activated protein kinase kinases (MEK) [73,74,75,76], which is consistent with our general understanding of the mitogen-activated protein kinase (MAPK) signaling pathway. The gene discussed is GPER1; the disease is breast carcinoma.