Fig. 3. Changes in distribution of traction stress generated by a wild-type Dictyostelium cell during a `rapid recoil' retraction. (A-F) A time series of traction vector maps obtained from a wild-type cell moving in the general direction indicated (arrow), corresponding to one cycle of movement. The highest 90th percentile traction stresses (red and purple regions) are located in a crescent-shaped region at the rear of the cell (A,B,C) prior to retraction (R in C) at the rear (arrow) then disappear abruptly following retraction (D-F). Regions of low traction stress (white to green regions) are consistently found at the front of the cell (A-F). Once retraction has occurred these regions allow for protrusion to begin (P in E,F). Bar, 3 µm. (G) Plots of the 90th percentile traction stress (red), instantaneous speed (green), cell area (blue) and shape factor (yellow) corresponding to panels A-F. The rapid recoil retraction (R) occurs between 9-12 seconds (C,D) as indicated by the two vertical dotted lines.