Junction-dependent migration of epithelial cells. (A) Wound healing assays of wild-type and CTNNA1-deleted (αEcat KO) DLD1 cells. (B) Migration distance of the marginal cells at 24 h after scratching of the culture. KO, αEcat KO cells. Values were obtained at 25 points in a culture photographed with a 4× objective. Three cultures were analyzed. *, P < 0.05; **, P < 0.01; ***, P < 0.001 (t test, one-sided). (C) Trajectories of five independent leader (blue) or follower (red) cells during a 6.5-h time span are drawn over a montage image of Video 1. Follower cells were chosen from the zone consisting of two to three cell rows right behind the leader cell zone. Graphs show migration speed of the individual cells (right) and directionality in their migration (left). Here, directionality is the ratio of the net path length to the total path length in 200 min. The migration speed and directionality were obtained for individual cells as temporal averages. **, P < 0.01 (t test, one-sided). (D) Trajectories of singly isolated cells recorded for 20-h MDCK + SNAIL, MDCK cells stably transfected with SNAIL. A549 + TGFβ, cells cultured in 5 ng/ml of TGF-β. Values in the vertical and horizontal axes are identical. (E) Migration speed of isolated cells. Videos used for D were analyzed to obtain migration speed of each cell by temporal averaging of its instantaneous speed, and then by averaging of the values across the ensemble. Error bars represent SEM. Scale bars, 200 µm for A; 10 µm for C.