N-WASP (Neural Wiskott Aldrich Syndrome Protein) regulates actin polymerization by activating the Arp2/3 complex and promotes the formation of actin-rich structures such as filopodia. Such actin-rich structures play critical roles in cell adhesion and cell motility. Analysis of the adhesion properties of N-WASP(+/+) and N-WASP(-/-) mouse embryonic fibroblasts to extracellular matrix proteins revealed that N-WASP is critical for cell adhesion to fibronectin. There was no significant difference in the localization of paxillin in the two cell lines, however the vinculin patches in WASP(+/+) cells were thicker and more prominent than those in N-WASP(-/-) cells. The beta 1 integrins in N-WASP(+/+) cells were found in large clusters, while beta 1 integrins were more dispersed in N-WASP(-/-) cells. The N-WASP(-/-) cells migrated more rapidly than N-WASP(+/+) cells in a scratch migration assay. Thus, our data suggest that N-WASP deficiency leads to reduced adhesion to fibronectin and increased cell motility. (C) 2007 Elsevier Inc. All rights reserved.