ISG15 and lung adenocarcinoma: To further elucidate the effect of ISG15 overexpression on lung adenocarcinoma growth through regulation of lymphocytes and in an immune-competent microenvironment, we utilized WT and stably overexpressed ISG15 (Lv-ISG15) LLC injected them subcutaneously into C57 BL/6 mice, respectively (5 mice each group, Fig. 2A).