FOXP3 and neoplasm: Analyses of the cellular make up of tumor-infiltrating leukocytes detected a reduced percentage of FoxP3+ (p = 0.001) CD4+CD25+ cells and IL-10+ (p = 0.0001) CD4+CD25+FoxP3+ cells in metformin-treated mice compared to the non-treated group (Figure 5D,E).