Of note, tumor-infiltrating lymphocytes including NK cells generally express higher levels of CD39, CD73 and/or CD38 (yet another adenosine-producing enzyme) [154, 155] as compared to their circulating counterparts [153, 156, 157], which (at least in some settings) results in the acquisition of immunosuppressive properties. The gene discussed is ENTPD1; the disease is neoplasm.