Emerging ligands control the specification of neural crest precursors. The progressive determination of neural crest (NC) precursors into different cell lineages is represented in the scheme with a code of colors. Superimposed on this, the collection of new growth factors appearing first in vertebrates is depicted. The role of each ligand in controlling the specification/survival of each particular neural crest derivative is indicated with a corresponding code of colors. alpha-MSH, alpha-melanocyte-stimulating hormone; End, endothelin; GDNF, glial-derived neurotropic factor; NT, neurotropin; Nppc, natriuretic peptide precursor.