Model of the mechanism by which the Disheveled protein stabilizes β-catenin in the dorsal portion of the amphibian egg. (A) Disheveled (Dsh) associates with a particular set of proteins at the vegetal pole of the unfertilized egg. (B) Upon fertilization, these protein vesicles are translocated dorsally along subcortical microtubule tracks. (C) Disheveled is then released from its vesicles and is distributed in the future dorsal third of the 1-cell embryo. (D) Disheveled binds to and blocks the action of GSK-3, thereby preventing the degradation of β-catenin on the dorsal side of the embryo. (E) The nuclei of the blastomeres in the dorsal region of the embryo receive β-catenin, while the nuclei of those in the ventral region do not.