Cell surface GPI-bound ligand for Eph receptors, a family of receptor tyrosine kinases which are crucial for migration, repulsion and adhesion during neuronal, vascular and epithelial development. Binds promiscuously Eph receptors residing on adjacent cells, leading to contact-dependent bidirectional signaling into neighboring cells. The signaling pathway downstream of the receptor is referred to as forward signaling while the signaling pathway downstream of the ephrin ligand is referred to as reverse signaling. With the epha2 receptor may play a role in bone remodeling through regulation of osteoclastogenesis and osteoblastogenesis (By similarity). Binds to the receptor tyrosine kinases epha2, epha3, epha4 and epha5. Interacts with epha8; activates epha8 (By similarity). Widespread expression in the embryo. Expressed in the presumptive midbrain of developing embryos from the six-somite stage. By 24 hours, expressed throughout the midbrain including the region of the presumptive tectum. At later stages, expressed in a graded fashion throughout the tectum. Belongs to the ephrin family.