Potency and selectivity of ML260. The potency of the inhibitor against dIAP (o), PLAP (+) and TNAP (x) was assessed by 16pt dose-response testing in 1536-well format in duplicate in 1xAssay Buffer, containing 100 mM DEA, pH 9.8, 0.02 mM ZnCl2, 1 mM MgCl2, and 1:250, 1:1000 and 1:2000 diluted enzymes, respectively, in a total volume of 4 μL/well. The reactions were started by addition of the CDP-star substrate to the final concentrations of 200 μM for the dIAP reaction, and 250 μM for the PLAP and TNAP reactions, with the luminescence intensity measured after 30 min incubation at room temperature.