Intersectin-1 (ITSN1), a guanine nucleotide exchange factor (GEF) for CDC42 is one of the binding partners of EPH receptors class B (EPHBs) in synapses. ITSN1 is expressed specifically in the brain and acts as the functional link between CDC42 and EPHB. EPHB2 receptor FORMS a complex with ITSN1 and N-WASP, triggers the activation of CDC42 to promote actin polymerization via N-WASP and the ARP2/3 complex, leading to spherical expansion of dendritic spine heads. EPHB co-immunoprecipitates with ITSN1, mediated by the kinase domain-containing fragment of EPHB and the amino (N)-terminal region of ITSN1 (Irie & Yamaguchi 2002).