FIGURE 5.

Contribution of a single stress fiber to cell traction forces and ECM mechanics visualized over time using traction force microscopy. Endothelial cells were transfected with YFP-actin and cultured on flexible fibronectin-coated polyacrylamide substrates containing embedded fluorescent nanobeads. A stress fiber was then irradiated and severed, and substrate stress and strain maps were calculated from the resulting bead displacements. (A) Spatial rearrangements of the actin cytoskeleton (green) and embedded beads (red). (Arrowhead indicates point of laser ablation; Bar = 20 μm). (These spatial changes are most clear in Supplemental Movie 4.) (B) Changes in bead displacements and ECM substrate strain distribution. (C) Changes in cell traction forces relaxed into the ECM substrate. Maps of substrate displacement (strain) and traction associated with single stress fibers were computed from bead positions before and after stress fiber incision.