EFNB2 and neoplasm: EphrinB2 is a cell surface transmembrane protein encoded by the EFNB2 gene in humans.1 It is widely expressed in tumour cells and mediates tumour cell proliferation, invasion and migration.2, 3 EphrinB2 can activate several Eph receptors (termed “forward” signalling), but can also serve as a receptor (“reverse signalling”).