The Wnt/Wg family encodes secreted glycoproteins implicated in cell growth regulation, cell fate determination, organogenesis and oncogenesis. Inferred from genetic analysis of wingless (wg) signaling in Drosophila, in mammalian cells, Wnts signal through the Frizzled family of receptors, to Dishevelled. Dishevelled down regulates glycogen synthase kinase-3 (GSK-3 ) activity. This results in the stabilization and accumulation of cytosolic -catenin, a GSK-3 substrate, which when phosphorylated by GSK-3, is targeted for ubiquitin-mediated proteolysis. -catenin then translocates to the nucleus, where in complexes with members of the Tcf/LEF family of transcription regulators, activates transcription of Tcf-responsive genes. This Tcf-reporter plasmid, along with FOPFLASH (Cat. # 21-169) enables quantitation of Wnt/Wg signaling in cells transfected with these constructs.