Ectonucleotidases are localized on tumor cells and different populations of immune cells that hydrolyze ATP or ADP into AMP via CD39 (ectonucleoside triphosphate diphosphohydrolase-1) and further process AMP into adenosine via CD73 (ecto-5′-nucleotidase) in the tumor microenvironment [48, 49]. Here, ENTPD1 is linked to neoplasm.