In structural and cell biology, the focal adhesion targeting domain is a conserved protein domain that was first identified in focal adhesion kinase (FAK), also known as PTK2 protein tyrosine kinase 2 (PTK2). Focal adhesions are multi-protein intracellular signalling complexes that link the cellular actin microfilament cytoskeleton, through the cell membrane via transmembrane integrin proteins, to the extracellular matrix. Focal adhesions form and dissipate as cells attach and detach from matrix during cell adhesion and cell migration.