Focal adhesion motility revealed in stationary fibroblasts

Focal adhesions (FAs) are clustered integrins and associated proteins that mediate cell adhesion and signaling. A green fluorescent protein-pi integri n chimera was used to label FAs in Living cells. in stationary cells, FAs w ere highly motile, moving linearly for several plaque lengths toward the ce ll center. FA motility was independent of cell density and resulted from co ntraction of associated actin fibers. In migrating cells, FAs were stationa ry and only moved in the tail. FA motility in stationary cells suggests tha t cell movement may be regulated by a clutch-like mechanism by which the af finity of integrins to substrate may be altered in response to migratory cu es.