To determine whether knockdown of Mig-6 and treatment with an EGFR-TKI has a synergistic effect in killing EGFR-TKI-resistant lung adenocarcinoma, we knocked down Mig-6 using shRNA and evaluated the effect on cell proliferation and EGFR-TKI sensitivity. The gene discussed is ERRFI1; the disease is lung adenocarcinoma.