To document further possible mechanisms for the antitumour activity of the immunosuppressive reagent temozolomide in association with the immunostimulatory immunocytokine F16–IL2, we have studied apoptosis and cell proliferation in glioblastoma xenografts after three doses of the four treatments: combination of F16–IL2 with temozolomide, F16–IL2 alone, temozolomide alone, and saline 10% DMSO. The gene discussed is IL2; the disease is glioblastoma.