Cell Crawling: First the Motor, Now the Transmission

Cell crawling is thought to be the result of three coordinated motility behaviors: (a) protrusion and adhesion of the front end, probably driven by actin assembly; (b) traction force that leads to the advance of the nucleus and bulk cytoplasm; and (c) release and retraction of the tail in most cell types. (In neurons, the last step is highly modified, and an axon elaborates from behind the advancing growth cone.) As Mitchison and Cramer (15) point out, it is the traction step that is least understood and seems most central to productive locomotion. Two papers in JCB now shed new light, both mechanical and molecular, on the traction step of cell crawling. A report in this issue of JCB on growth cone movements from the Forscher group (19) and a paper from the Borisy lab (20)...