Testing the specificity of CD39 inhibitor POM1 (A) and CD73 inhibitor AMP-CP (B) on the activity of different kinases, ATPase, as well as CD39 and CD73. Enzyme tested are protein serine/threonine/tyrosine, lipid, sugar, and inorganic kinases, and K/Na ATPase. Results show that the majority of enzymes are inhibited by POM1 (A), but the more selective CD73 inhibitor AMP-PC) was highly selective for CD73 with minimal inhibition for PKA and no inhibition of the other enzymes. PKA, protein kinase A (solid circle), PKCα (solid square), Src, protein tyrosine Src kinase (solid triangle), Acka, acetate kinase from Escherichia coli (solid reverse triangle), HK, hexokinase from Saccharomyces cerevisiae (solid circle), PI3αKinase, p110α/p85α (square), K/K ATPase, Adenosine 5´-Triphosphatase from porcine cerebral cortex (circle), CD39 (ATP substrate, triangle), and CD39 (ADP substrate, reverse triangle); for CD73 (triangle) in panel B. Each point represents average of a typical experiment done in triplicates; results shown are mean ± SD.