The largest subfamily of receptor protein-tyrosine kinases consists of receptors related to Eph, a receptor named for its expression in an Math Eq rythropoietin-Math Eq roducing human Math Eq epatocellular carcinoma cell line. This subfamily has received considerable attention as receptors and their ligands have been identified at a dizzying pace in recent years and implicated in cell–cell interactions involved in nervous system patterning, including axon guidance, and in other aspects of development. To date, fourteen distinct receptors of this subfamily and eight distinct ligands have been identified in warm-blooded vertebrates (mammals and birds), with many related proteins identified in cold-blooded vertebrates and in invertebrates.

Because of the rapid pace of discovery of receptors and ligands in various species, many different names have been used to designate them, making it difficult for the general scientific community to follow developments in this exciting field. To address this problem, representatives of over 20 laboratories involved in research on the Eph family initiated extensive discussions at the “Molecular Biology of Axon Guidance” workshop held at the EMBL, Heidelberg, in September, 1996. As a result, a proposal was put forth to unify and to systematize the nomenclature for these ligands and receptors, and an Eph Nomenclature Committee was elected to refine the proposal in consultation with the community at large. The resulting nomenclature has now been endorsed by over 70 scientists, 1 many of whom contributed extensively to defining the nomenclature and to preparing this letter, as well as by the Human and Mouse Gene Nomenclature Committees.