The Wnt family includes several secreted glycoproteins that play important roles in animal development. There are 19 Wnt genes in the human genome that encode functionally distinct Wnt proteins. Wnt members bind to the Frizzled family of seven-pass transmembrane proteins and activate several signaling pathways. Wnt3a and Wnt3 are ligands for members of the frizzled family of seven transmembrane receptors. Wnt3a plays distinct roles in cell-cell signaling during morphogenesis of the developing neural tube. It ligands for members of the frizzled family of seven transmembrane receptors.