The formation of invadopodia relies on lamellipodia and filopodial machineries. (A) Immunoblot analysis after siRNA treatment. Scrambled siRNA served as a control for the nonspecific cell response (si-control). Tubulin served as a loading control. (B and C) Quantification of the gelatin degradation of MDA-MB-231 cells treated with the indicated siRNA and normalized to the cells treated with a scrambled siRNA (si-control). (B) Percentage of cells that degraded the gelatin. (C) Degradation index was calculated as described in Materials and methods. (B and C) Error bars indicate SEM. *, P < 0.001; Kruskal-Wallis analysis of variance, Holm-Sidak method. (D) Time-lapse analysis of invadopodia lifetime. Each graph shows the distribution of invadopodia lifetimes in each of the conditions as indicated. Statistical differences were observed between si-control and si-fascin and si-control and si-p34 but not between si-control and si-myosinX (P < 0.001; Kruskal-Wallis analysis of variance, Dunn’s method).