PAKs can associate with cortactin (CTTN), a cortical actin binding protein, irrespective of the activation status of PAKs. Once activated, PAKs phosphorylate cortactin, predominantly at Ser113 in the first actin-binding repeat. Cortactin phosphorylation modulates its interaction with actin and actin cytoskeleton regulators and is involved in cell motility (Weed et al. 1998, Vidal et al. 2002, Webb et al. 2006, Grassart et al. 2010, Moshfegh et al. 2014).