FOXP3 and neoplasm: Supplementary Figure S4 shows that approximately 40% of CD4+ T cells in central tissues were Tregs, and that the majority of CD39+ CD4+ T cells were also positive for CD25 and FOXP3. This suggests that most CD39+ CD4+ T cells display a Treg phenotype and may, therefore, not function as tumor-reactive T cells in pancreatic cancer.