Growth Associated Protein-43(GAP-43), also known as nerve growth-related growth peptide GAP43, shares a high degree of homology between the sequence of the human gene and the rat gene. GAP-43 is considered a crucial component of an effective regenerative response in the nervous system. Somatic cell hybrids demonstrate localization of the GAP-43 gene to human chromosome 3 and to mouse chromosome 16. GAP-43 has been termed a "growth" or "plasticity" protein because it is expressed at high levels in neuronal growth cones during development and during axonal regeneration. GAP-43 regulates growth of axons and modulates the formation of new connections.