CTLA4 and neoplasm: When spleens of rats with a diethylnitrosamine-induced liver cancer were irradiated at 0.15 Gy from the 6 MeV β-beam accelerator at 100 mGy/min dose rate, the percentage of CD4+CD25+ Treg cells in the blood significantly decreased and the levels of Foxp3, IL-10, TGF-β, and CTLA-4 were down-regulated in the spleen and the tumor; these changes were accompanied by the suppressed tumor growth [175].