Description: 123B9 is a tumor-homing agent characterized as a potent and selective agonist for EphA2 with a dissociation constant (Kd) of 4.0 μM. It specifically targets the ligand-binding domain of the EphA2 tyrosine kinase receptor. Notably, 123B9 does not significantly inhibit the ligand-binding domains of closely related receptors EphA3 and EphA4.