With increasing concentration, the proliferation activity of A549 cells gradually increased, but when the concentration reached 200 ng/mL, the proliferation activity of A549 cells did not continue to increase, and the proliferation activity of A549 cells decreased thereafter, which indicated that a low concentration of IFN-γ could promote the proliferation of lung adenocarcinoma cells, while a high concentration of IFN-γ inhibited proliferation. The gene discussed is IFNG; the disease is lung adenocarcinoma.