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