Wnt signaling proteins are small secreted proteins that are active in embryonic development, tissue homeostasis, and tumorigenesis. HLY78 is a positive modulator of the Wnt/β-catenin pathway, as it augments Wnt-mediated signaling in cells at concentrations of 5 to 20 μM. It has no significant effect alone, and it does not affect LiCl-stimulated β-catenin signaling. A biotinylated form of HLY78 binds Axin at its DIX domain, which is thought to potentiate Axin-LRP6 association. HLY78 activates Wnt signaling in vivo, altering Wnt-dependent gene expression and embryonic development in zebrafish.