IL15 and glioblastoma: The concentration of IL-15 reached higher values at 96 h after infection of GBM cells, 10.325, 12.97 and 19.32 pg/ml in GL261, U251 and U87 cells, respectively, while primary cells BT-01 appeared to reach a higher value of 9.71 pg/ml 72 h post transfection (Fig. 1a–d), demonstrating that Ad5-Ki67/IL-15 mediates efficient and stable expression of IL-15.