SHB binds focal adhesion kinase 1 (FAK1; also known as PTK2) via its PTB domain in a phosphotyrosine-dependent manner. This regulates FAK1 phosphorylation, leading to Src dependent enhanced cell spreading (Holmqvist et al. 2003). During vascular development, FAK1 is involved in the control of endothelial cell migration (Holmquist et al. 2004), vascular permeability (Chen et al. 2012) and tube formation (Bohnsack & Hirshi, 2003).