IWP-2 is an inhibitor of Wnt processing and secretion with an IC50 of 27 nM. IWP-2 targets the membrane-bound O-acyltransferase porcupine (Porcn) and thus preventing a crucial Wnt ligand palmitoylation. IWP-2 is also an ATP-competitive CK1δ inhibitor with an IC50 of 40 nM for the gatekeeper mutant M82FCK1δ[1][2].