EPHA1,also named as EPH,EPHT and EPHT1,belongs to ephrin receptor subfamily of the protein-tyrosine kinase family. EPH and EPH-related receptors have been implicated in mediating developmental events,particularly in the nervous system. Receptors in the EPH subfamily typically have a single kinase domain and an extracellular region containing a Cys-rich domain and 2 fibronectin type III repeats. Ligands in the ephrin-A subclass,including the prototype family member ephrin-A1 (B61),are membrane associated through glycosylphosphatidyl-inositol linkages,whereas ephrin-B subclass consists of ligands with transmembrane domains. The general role of the Eph family is in mediating repulsive cell-cell interaction.