Nodal is a secretory protein that in humans is encoded by the NODAL genewhich is located on chromosome 10q22.1. It belongs to the transforming growth factor beta (TGF-β) superfamily. Like many other members of this superfamily it is involved in cell differentiation in early embryogenesis, playing a key role in signal transfer from the node, in the anterior primitive streak, to lateral plate mesoderm (LPM).Nodal signaling is important very early in development for mesoderm and endoderm formation and subsequent organization of left-right axial structures.In addition, Nodal seems to have important functions in neural patterning, stem cell maintenanceand many other developmental processes, including left/right handedness.