| Modification Notes |
The Wnt genes are a group of well conserved, cysteine-rich secreted glycoproteins that are required for numerous develop-mental processes including embryogenesis, asymmetric cell division and central nervous system (CNS) patterning (1,2). Wnt association with the seven membrane spanning receptor Frizzled, activates Dishevelled, which downregulates glycogen synthase kinase (GSK) (through serine phosphorylation), causing the accumulation of b-Catenin and the regulation of developmentally significant Wnt target genes (2-4). The Dickkopf family of secreted inhibitors of Wnt signaling ensures proper morpho-logical development by antagonizing different stages of the Wnt cascade (4,5). Dkk-4 (Dickkopf-4) is a 224-amino acid secreted glycoprotein that is composed of an N-terminal signal peptide and 2 conserved cysteine-rich domains, which are separated by a 50-55-amino acid linker region (6,7) |