A major advance has been the discovery that F1-ecto-ATPase is a receptor for apolipoprotein A-I (apoA-I) (32, 39) and that apoA-I is necessary for Vγ9Vδ2 T-cell activation by tumor cells expressing IPP/ApppI-loaded F1-ecto-ATPase (32). The gene discussed is ENTPD2; the disease is neoplasm.