EphB2 Antibody (2D12C6)

The Eph receptors are the largest known family of receptor tyrosine kinases (RTKs). They can be divided into two groups based on sequence similarity and on their preference for a subset of ligands: EphA receptors bind to a glycosylphosphatidylinositol-anchored ephrin A ligand, and EphB receptors bind to ephrin B proteins that have a transmembrane and cytoplasmic domain [1,2]. Eph receptors and ligands may be involved in many diseases including cancer [3]. Both ephrin A and ephrin B ligands have dual functions. As RTK ligands, the ephrins stimulate the kinase activity of the Eph receptors and activate signaling pathways in receptor-expressing cells. The ephrin extracellular domain is sufficient for this function as long as it is clustered [4]. The second function of ephrins has been described as "reverse signaling," whereby the cytoplasmic domain becomes tyrosine phosphorylated, allowing interactions with other proteins that may activate signaling pathways in the ligand-expressing cells [5]. Various stimuli can induce tyrosine phosphorylation of ephrin B, including binding to EphB receptors, activation of Src kinase and stimulation by PDGF and FGF [6]. Tyrosines 324/327 have been identified as major phosphorylation sites of ephrin B1 in vivo [7].