JW55 is a small molecule inhibitor of the Wnt/β-catenin signaling pathway that functions via inhibition of the PARP domain of tankyrase 1 and tankyrase 2 (TNKS1/2), regulators of the β-catenin destruction complex. Inhibition of TNKS1/2 poly(ADP-ribosyl)ation activity by JW55 leads to stabilization of AXIN2, a member of the β-catenin destruction complex, followed by increased degradation of β-catenin. In a dose-dependent manner, JW55 inhibits canonical Wnt signaling in colon carcinoma cells that contained mutations in either the APC (adenomatous polyposis coli) locus or in an allele of β-catenin. MW: 434.48. Purity >98% by HPLC