Dorsal stress fibers in motile cells are formed from actin filament bundles that are initiated and extended from cell-substrate adhesions at the leading edge (aka focal complexes. Initiation is triggered by the activation of adhesion molecules, such as integrin, and the tension-dependent recruitment and activation of the Rho family of GTPases, including Rac1. Assembly then takes place, with filament elongation and condensation being the primary steps involved. Assembly of dorsal stress fibers and transverse arcs appears to be connected: transverse arcs encounter dorsal stress fibers as they are transported towards the cell body via cell-wide actin-myosin contractions… Read more…