CD73 (Ecto-5′-nucleotidase), a component of the purinergic signaling pathway, is a 70-kD glycosylphosphatidylinositol-anchored cell surface protein encoded by the NT5E gene.

CD73 has both enzymatic and non-enzymatic functions in cells. As a nucleotidase, CD73 catalyzes the hydrolysis of AMP into adenosine and phosphate, and CD73-generated adenosine plays an important role in tumor immunoescape. CD73 plays a crucial role in switching on adenosinergic signaling. CD73 also functions as a signal and adhesive molecule that can regulate cell interaction with extracellular matrix components, such as laminin and fibronectin, to mediate the invasive and metastatic properties of cancers. Both the enzymatic and non-enzymatic functions of CD73 are involved in cancer-associated processes and are not completely independent of each other.

Overexpression of CD73 is associated with resistance to antitumor agents. Knockdown of CD73 inhibits in vitro cell growth, cell cycle progression and cell migration in many cancers. CD73 and its associated pathways may be useful as therapeutic targets.