ENTPD1 and metastatic neoplasm: ENTPD1 expressed on CD4+Foxp3+ regulatory T cells (Tregs), and in mice, it could inhibit natural killer (NK) cells and promote hepatic metastatic tumor growth, whereas inhibition of the enzymatic activity of ENTPD1 could be used as an adjunct therapy for hepatic malignancies (Sun et al., 2010).