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). The gene discussed is ENTPD1; the disease is neoplasm.