Mouse Ephrin‑A4 is a GPI‑anchored member of the ephrin‑A ligand family that regulates cell–cell communication through binding to EphA receptors, including EphA2, EphA4, and EphA7. It plays essential roles in axon guidance, neuronal patterning, tissue boundary formation, and immune cell positioning. Ephrin‑A4–mediated signaling contributes to developmental processes and has emerging relevance in cancer biology, where Eph/ephrin interactions influence tumor growth, migration, and microenvironment remodeling. Fc‑fusion formats enhance stability and receptor engagement for in‑vitro studies.