Sticky fingers for migration

Roaming cells send out sticky fingers to probe for good attachment points, say Catherine Galbraith, Kenneth Yamada, and James Galbraith (NIH, Bethesda, MD). The fingers' sideways movements give cells a wider field of vision than do forward and reverse movements alone.

These sideways movements were picked up by the authors as ripples in the plasma membrane at the very front of a migrating fibroblast. The ripples were made by polymerizing actin filaments that elongated nearly parallel to the lamellipodial leading edge. Their quick polymerization moved the ripples several times faster than lamellipodia can extend forward.

The tips of the actin filaments at the ripple crests were attached to ready-to-bind adhesion receptors. Although not yet bound to the matrix, these β₁ integrins were in a conformation that readily binds to...