Kinase-defective receptor for members of the ephrin-B family. Binds to ephrin-B1 and ephrin-B2. Modulates cell adhesion and migration by exerting both positive and negative effects upon stimulation with ephrin-B2. Inhibits JNK activation, T-cell receptor-induced IL-2 secretion and CD25 expression upon stimulation with ephrin-B2 (By similarity). Interacts with CBL and EPHB1. Interacts with FYN; this interaction takes place in a ligand-independent manner (By similarity). Additional isoforms seem to exist. High level in thymus, and brain. Very low levels of expression in kidney, lung, liver, bone marrow, skeletal muscle, spleen from 2 week old and adult mice, heart, testes and embryonic stem cells. The protein kinase domain is predicted to be catalytically inactive. Its extracellular domain is capable of promoting cell adhesion and migration in response to low concentrations of ephrin-B2, but its cytoplasmic domain is essential for cell repulsion and inhibition of migration induced by high concentrations of ephrin-B2 (By similarity). Ligand-binding increases phosphorylation on tyrosine residues. Phosphorylation on tyrosine residues is mediated by transphosphorylation by the catalytically active EPHB1 in a ligand-independent manner. Tyrosine phosphorylation of the receptor may act as a switch on the functional transition from cell adhesion/attraction to de-adhesion/repulsion (By similarity). Belongs to the protein kinase superfamily. Tyr protein kinase family. Ephrin receptor subfamily.