Effects of PDGF-AA and EIPA in wound-healing assays on growth-arrested WT MEFs. (A) Trajectories (normalized to common starting points) of growth-arrested WT MEFs in the presence of 50 ng/ml PDGF-AA and in the absence or presence of 10 µM EIPA, as indicated. The radii of the red circles illustrate the mean translocation of the cells within a 5-h time period. (B) Translocation (in micrometers) of growth-arrested WT MEFs in the absence or presence of 50 ng/ml PDGF-AA and 10 µM EIPA, as indicated, calculated as described in the legend for Fig. 3. (A and B) Data shown are individual trajectories (A) or means ± SEM (B) of 20–53 cells in three to seven independent experiments. Data were analyzed using parametric or nonparametric ANOVA, and the level of significance is shown (***, P < 0.001). (C) Images of the left side of the wound in a confluent monolayer of growth-arrested WT MEFs at time 0 and 4 h after the wound was made. The arrows indicate the x and y directions of movement, which were used for estimating directional migration. (D) Velocity of migration perpendicular to the wound (x direction) in PDGF-AA–stimulated, growth-arrested WT MEFs in the absence (open circles) or presence (closed circles) of EIPA. Directionality of movement was estimated by plotting the mean of the distance covered by each cell in the x direction as a function of time. The slope of this line yields the velocity in the x direction (in micrometers/minute), which is a measure of directionality. The velocity in growth-arrested, PDGF-AA–treated WT MEFs was 0.301 ± 0.003 µm/min in the absence and 0.030 ± 0.004 µm/min in the presence of 10 µM EIPA. Data shown are means ± SEM of 20–53 cells in three to seven independent experiments. The velocity in the presence of EIPA is significantly different from that in the absence of EIPA (P < 0.0001). Ctrl., control.