CD4 and neoplasm: Of note, the membrane co-expression of CD25 and CD39 in CD4+ T-cells allowed us to detect a median 66.8% [2.5–95.9] of FoxP3+ cells, suggesting that their co-expression could offer an option to identify Tregs when FoxP3 intracellular staining is not feasible (e.g. flow cytometry applied to fresh tumor biopsies in the context of clinical trials).