IWP-3 is a selective small molecule wnt inhibitor, prevents palmitylation of Wnt proteins by Porcupine (Porcn), a membrane-bound O-acyltransferase, thereby blocking Wnt secretion and activity1. It blocks phosphorylation of the Lrp6 receptor and accumulation of both Dvl2 and β-catenin. It has an IC50 of 40 nM which is 100 folds less potent than Wnt-C59, but it can still efficiently promote cardiomyocyte differentiation from human ESCs.