Plasmids (Notum wild-type and Notum S239A mutant) are described elsewhere.(11 (link)) Cells were seeded at 70% confluence in 6-well plates and transfected with plasmids (Empty vector, NTM WT and NTM S239A) (2μg) using either Lipofectamine 2000 (Invitrogen) or Mirus TransIT-LT1 (Mirus) for 48 hours and transferred to 24-well plates for further assay. Mouse recombinant Notum protein was synthesized and provided by Indiana Biomedical Research Institute (IBRI).