ENTPD1 and neoplasm: The A2a receptor is constitutively expressed by T cells and has higher affinity for adenosine than the A2b receptor.54 When these receptors are stimulated with adenosine, cAMP is generated through adenylyl cyclase, which triggers protein kinase A and inhibits Tconvs proliferation and function.55 In murine tumor models, CD39 and CD73 expressed by Tregs reduce ATP and produce adenosine, which suppresses antitumor effector T cells.