Paxillin, a focal adhesion protein, is involved in focal adhesion formation during cell adhesion and migration. Paxillin contains LD motifs, LIM domains, and SH3-/SH2-binding domains that participate in a variety of protein-protein interactions with kinases, GTPase-activating proteins, and cytoskeletal proteins. Phosphorylation of paxillin occurs at both tyrosine and serine sites. Serine phosphorylation of paxillin occurs in response to growth-factor activation and fibronectins. Both JNK1 and cdc2 kinases can phosphorylate serine 178 in paxillin. The mutant form of paxillin (S178A) decreases the migration of keratocytes and epithelial cells. Thus, phosphorylation paxillin at serine 178 may be important during cell migration
