Activation of the epidermal growth factor receptor (EGFR) is a key signaling event that promotes cells to move and cover wounds in many epithelia. We have previously shown that wounding activates the EGFR through activation of the Src family kinases (SFKs), which induce proteolytic shedding of epidermal growth factor-like ligands from the cell surface. A major goal in wound healing research is to identify early signals that promote motility, and here we examined the hypothesis that members of the focal adhesion kinase family are upstream activators of the SFKs after wounding. We found that focal adhesion kinase is not activated by wounding but that a different family member, Pyk2 (PTK2B/RAFTK/CAK), is activated rapidly and potently. Pyk2 interaction with c-Src is increased after wounding, as determined by co-immunoprecipitation experiments. Disruption of Pyk2 signaling either by small interfering RNA or by expression of a dominant negative mutant led to inhibition of wound-induced activation of the SFKs and the EGFR, and conversely, overexpression of wild-type Pyk2 stimulated SFK and EGFR kinase activities in cells. In wound healing studies, Pyk2 small interfering RNA or dominant negative inhibited cell migration. These results show that activation of Pyk2 is an early signal that promotes wound healing by stimulating the SFK/ EGFR signaling pathway.Wounding induces profound changes in adjacent epithelial cells, which include rearrangement of the actin cytoskeleton, internalization of cell junction proteins, and redistribution of membrane phospholipids (1-4), and they subsequently acquire a phenotype that allows them to migrate rapidly (5, 6). Activation of the epidermal growth factor receptor (EGFR) 2 tyrosine kinase (7, 8) is an obligatory signaling event that stimulates a multitude of downstream effectors to induce these changes in many epithelia, including the gut, airway, epidermis, and cornea (9 -14). Understanding the molecular mechanisms of wound-induced EGFR activation is central to understanding how epithelia acquire a motile phenotype.The proximal event for activation of the EGFR is proteolytic release of transmembrane ligands, such as heparin-binding EGF-like growth factor, by a mechanism that resembles transactivation of the EGFR by G-protein coupled receptors (15)(16)(17)(18)(19)(20). Recent data suggest that the Src family kinases (SFKs) control EGFR ligand shedding after wounding (5, 21). The SFKs are ubiquitously expressed non-receptor tyrosine kinases that regulate cytoskeletal dynamics, cell/matrix interactions, and transduction of extracellular signals (22). The SFKs contain Src homology 2 and 3 domains that bind to consensus phosphotyrosine and proline-rich domains, respectively, which can lead to activation by loss of inhibitory intramolecular interactions (23).We have recently found that SFKs and the EGFR are activated rapidly in cells within 250 m of the wound edge (5). In addition, extracellular ATP is released from cells and can induce activation of the EGFR further from the wounds. How...