JW 55 is an inhibitor of the PARP domain of tankyrases (TNKS) 1 and 2 (IC50s = 1.9 and 0.83 µM, respectively). By inhibiting TNKS1/2, JW 55 stabilizes Axin2 and increases degradation of β-catenin, inhibiting the β-catenin signaling pathway (IC50 = 470 nM). It has been shown to decrease canonical Wnt signaling in SW480 and HCT15 colon carcinoma cell lines and to reduce proliferation of SW480 cells in vitro.