Isolation and application of bioactive Wnt proteins.

Wnt proteins and their signaling cascades are involved in a wide variety of developmental processes, and deregulation of this pathway is frequently associated with tumorigenesis. Unlike many other growth factors, Wnts long eluded biochemical purification, in large part because of their hydrophobic nature, which is imparted by one or more lipid modifications. Here I describe a complete protocol that outlines the purification process for Wnt proteins. While this protocol has not been applied to all known Wnt proteins, it has been successfully applied to the purification of a large subset of Wnts, including the very divergent Wnt protein, Drosophila Wnt8 (Dwnt8 or WntD), indicating that this protocol is likely applicable to all Wnts.