ENTPD1 and neoplasm: Extracellular Ado (eAdo) accumulation may result from elevated eATP levels as well as increased expression of CD39 and CD73, two major ectonucleotidases for eATP hydrolysis, to varying degrees in UQCRC1-overexpressing PANC-1 cells (Figures 4C, D) and tumor xenografts (Figures 4E, F).