Fig. 6. Response of cell migration and traction forces to local application of Gd³⁺ near the trailing edge. Phase contrast images (A-C) of a migrating NIH3T3 fibroblast, recorded immediately before (A) or at specified time points after the application of 100 µM Gd³⁺ near the trailing edge, showed no apparent effect on cell morphology or migration. Asterisks mark a fiduciary reference point on the substratum. The corresponding traction stress images (D-F), with different colors representing the magnitude, from 7.63x10¹ dynes/cm² (violet) to >4.75x10⁴ dynes/cm² (red), showed no apparent effect on traction stress following the local Gd³⁺ application. Scale bar: 20 µm.