An inhibitor of Wnt production. Blocks Wnt pathway activity in vitro ( IC₅₀ = 40 nM). IWP-3 inactivates Porcupine (Porcn), a membrane-bound O-acyltransferase responsible for palmitoylating Wnt proteins, which is essential for their signaling ability and secretion. Through blockade of Wnt signaling, IWP-3 has been used to promote cardiomyocyte generation from human embryonic stem cells (EC₅₀ = 1.2 μM).