EphB4: EPH receptor B4, also known as Htk, Myk1, Tyro11. Entrez Protein: NP_004435. It is a member of the Eph receptor family, which bind the ephrin ligand family. Based on their structures and sequence relationships, ephrins are divided into the ephrin-A (EFNA) class, which are anchored to the membrane by a glycosylphosphatidylinositol linkage, and the ephrin-B (EFNB) class, which are transmembrane proteins. Ephrin receptors make up the largest subgroup of the receptor tyrosine kinase (RTK) family. The EphB4 protein binds to ephrin-B2 and plays an essential role in vascular development.