RhoA and mDia1 restore lamellipodial α-actinin and cell motility in Memo-depleted cells. SKBR3 cells were transfected with Memo, mDia1, or control siRNA, and constructs coding for Memo, active mDia1 (mDia1[ΔN3]), or active RhoA (RhoAV14) as indicated. (A) α-Actinin-1 labeling was analyzed as in Fig. 2 D. Width of α-actinin–labeled lamellipodia was measured along the cell leading edge. Values are means ± SEM (10 regions per cell for 18 cells; three independent experiments). *, P < 0.025 by Kruskal-Wallis. (B) Cell velocity was determined by tracking cells every 5 min for 150 min. 90–150 cells were tracked per condition. Values are means ± SEM from three independent experiments. *, P < 0.05; **, P = 0.07 (note that P = 0.002 when n = 9) by Kruskal-Wallis.