ENTPD1 and melanoma: In a murine model of hepatic metastatic cancer, resulting from portal vein infusion of MCA38 colon cancer cells and melanoma B16/F10 cells, ENTPD1/CD39 expression on Tregs strongly suppresses natural killer (NK)-mediated anti-tumor immunity (59); whereas ENTPD1/CD39 inhibition restores anti-cancer responses, significantly limiting tumor growth (58, 59).