CD73, also known as Ecto-5'-nucleotidase, is an ectoenzyme that is attached to the cell membrane by a glycosyl phophatidylinositol anchor. The enzyme is expressed by most cell types. The 5’-Nucleotidase activity of CD73 converts extracellular nucleoside-5’-monophosphates to nucleosides. CD73 is one of several enzymes responsible for the production of extracellular adenosine, a signaling molecule that is involved in responses to inflammation and tissue injury. CD73 hydrolyzes extracellular nucleotides into membrane permeable nucleosides.