Fig. 5. Response of cell migration and traction forces to local application of Gd³⁺ near the leading edge. Phase contrast images (A-C) of a migrating NIH3T3 fibroblast, recorded immediately before (A) and at specified time points after the application of 100 µM Gd³⁺ near the leading edge (arrows, B,C), showed no inhibition of local protrusive activities (arrows), although the cell body failed to migrate forward. Asterisks mark a fiduciary reference point on the substratum. The corresponding traction stress images (D-F), with different colors representing the magnitude, from 4.25x10¹ dynes/cm² (violet) to >4.50x10⁴ dynes/cm² (red), showed a global decrease in traction stress following the local Gd³⁺ application. Scale bar: 20 µm.