IL2 and lung adenocarcinoma: We mixed lung adenocarcinoma, A549 cells (5×103) per well together with different ratios of NK cells (NK cells: A549 cells=0.5:1, 1:1, 2:1, 4:1) in 96-well plate either in the presence or absence of 100U/mL of IL-2 for 24 h.