NT5E and cancer: Adenosine production and transportation in cancer tissues are similar to physiological conditions; extracellular ATP and ADP can rapidly metabolize to adenosine monophosphate (AMP) majorly through two steps of dephosphorylation: 1) The first step, ATP and ADP are both converted to AMP by ecto-nucleoside triphosphate diphosphohydrolase-1 (CD39); then 2) AMP can generate adenosine by the final dephosphorylation reaction catalyzed by the enzyme ecto-5′-nucleotidase (CD73) (Fishman et al., 2009b) - this called CD39/CD73 pathway.