Adenosine, produced by Cluster of Differentiation 39 (CD39) and Cluster of Differentiation (CD73) in the tumor microenvironment as an extrinsic immunosuppressive mechanism, binds to the Adenosine A1 Receptor, Adenosine A2A Receptor, Adenosine A2B Receptor and Adenosine A3 Receptor receptors, thereby inhibiting T cell activity and promoting Treg accumulation. This evidence concerns the gene ENTPD1 and neoplasm.