Polypeptides which bind to one or more EPH-like receptors, particularly the HEK4 receptor, are described. The polypeptides are designated HEK4 binding proteins. Nucleic acids encoding HEK4 binding proteins, and expression vectors, host cells and processes for the production of the polypeptides are also described. The polypeptides are useful for modulating the growth and/or differentiation of a variety of tissues, including those from liver, kidney, lung, skin, digestive tract and nervous system and may be used to regenerate damaged or depleted tissue and to treat cancer or nervous system disorders.