Focal adhesion kinase 1 (PTK2, FAK, FAK1) activation plays a critical role in EPHB receptor signaling in dendritic spines. PTK2 has six tyrosine phosphorylation sites, with tyrosine 397 being the main auto-phosphorylation site present upstream of the kinase domain (Schaller et al. 1994). Activation of EPHB receptors induces long-lasting phosphorylation of PTK2 on tyrosine 397 (Shi et al. 2009). This phosphorylated tyrosine then creates a binding site for other signaling proteins that link PTK2 to downstream signaling pathways and actin cytoskeleton.