Eph receptors and ligands comprise two major specificity subclasses and are reciprocally compartmentalized during embryogenesis. - Gale,NW.; Holland,SJ.; Valenzuela,DM.; Flenniken,A.; Pan,L.; Ryan,TE.; Henkemeyer,M.; Strebhardt,K.; Hirai,H.; Wilkinson,DG.; Pawson,T.; Davis,S.; et al. (Neuron, 1996)