ENTPD1 and neoplasm: Recently, numerous promising attempts have been made to differentiate these populations comprehensively, either through markers of tumor specificity (i.e., CD39, CD103, PD1) (1–3) or tumor reactivity (de novo antitumor cytokine production, mobilization of cytotoxic granules, upregulation of activation markers following recognition of autologous tumor-antigens) (4–6).