However, the role of GPER1 in estrogen signaling pathway and the association between its expression and EGFR mutation in lung adenocarcinoma are less well understood, and few studies have integrated analyzed the expression of ERα, ERβ and GPER1 and their association with clinicopathological factors, namely, EGFR and KRAS mutation (8). The gene discussed is ESR1; the disease is lung adenocarcinoma.