The α- c atenin–vinculin interaction regulates cell edge activity and stress fiber formation. (A) Color-coded time-series of the cell edge of α-catenin KD cells expressing WT GFP-α-catenin (left) and GFP-α-catenin L344P (right), showing much higher cell edge activity in the latter. (B) Average of six frames (equivalent to 2 min) from a video zoomed-in on the edge of a cell expressing GFP-α-catenin L344P and mCherry-vinculin; the bottom right image is a kymograph taken from the yellow line shown in the bottom left image. Note the difference in speed (slope) between vinculin (purple arrow) and α-catenin L344P (green arrow). (C) Frame from a video (Video 10) of an α-catenin KD cell expressing GFP-α-catenin L344P and td-Tomato-Tractin, showing aggregation of both at the cell center. (D) Rate of translocation of stress fibers in cells expressing WT GFP-α-catenin and GFP-α-catenin L344P, as measured from kymographs specifically focused on transverse arc type of stress fibers. N > 25 stress fiber retraction events from eight cells each. (E) Micrographs of α-catenin KD cells expressing WT GFP-α-catenin and GFP-α-catenin L344P, stained for F-actin (phalloidin). The yellow arrows point to actin aggregates near the cell center. (F) Micrographs of α-catenin KD cells expressing GFP-ABD and GFP-α-catenin L344A, stained for F-actin (phalloidin). The yellow arrows point to actin aggregates near the cell center. Statistical analysis for the stress fiber translocation rate was performed with two-tailed unpaired t test followed by Welch’s correction (****, P < 0.0001).