May be a signaling molecule that mediates inductive activities of the embryonic midline. Able to dorsalize mesoderm. Expression starts at the mid-gastrula stage in the dorsal midline. Expressed in the axial mesoderm at this stage. At neurula stages, expression is detected both in the axial mesoderm (notochord and prechordal mesoderm) and in the ventral central nervous system (floor plate and ventral forebrain). At tailbud stages, expression is diminished in the notochord and remains in the ventral central nervous system (CNS). During and after tailbud stages, other regions shows detectable levels of expression. The epiphyseal placode has a strong expression. Additional expression is found in dorsal parts of the CNS, especially in the anterior spinal cord and hindbrain as well as in the tailbud mesoderm. At the larval stage, expression is also found in the forming heart. Induced in mesoderm and in ectoderm by nodal-related genes. 'Kiel' means keel in English. As the expression in the central nervous system (CNS) resembled a keel of ship, the gene was named Kielin.