Notes: ZM 522 is an inhibitor of ecto-5'-nucleotidase, also known as CD73 (IC50s = 0.56 and 3.06 µM for the human and mouse enzymes, respectively), and a derivative of the triterpenoid betulinic acid (Item No. 11686).{66372} It increases the levels of IFN-γ secreted by isolated mouse spleen cells when used at a concentration of 10 µM in the presence of AMP.