PFI-653 (Vanin-1-IN-1, compound 3), a chemical probe, is a vanin-1 inhibitor that binds to plasma vanin-1 from mouse, rat, dog, and human. Vanin-1 is a cell surface-associated inositol (GPi) -anchored protein that plays important roles in metabolism and inflammation. PFI-653 inhibits vanin-1 from different species with IC50s of 6.85 nM (human recombinant plasma vanin-1), 9.0 nM (human plasma vanin-1), 24.5 nM (mouse recombinant vanin-1), and 53.4 nM (mouse plasma vanin-1) [1][2].