Fig. 7

Invadopodial force production is powered by actin polymerization. a MDA-MB-231 cells expressing Tks5^GFP (green) were plated on a thin layer of type I collagen (magenta) and imaged over time. Cytochalasin D (0.5 µM) was added 15 min after starting the time-lapse. Representative frames (time in hr:min) show rapid disassembly following CytoD treatment and limited collagen-fiber remodeling (Supplementary Movie 5). The cell contour is shown with a dashed line. Scale bar, 10 µm. The lower row represents separate channels in the boxed region. Scale bar, 5 µm. b–g Kymograph analysis of radial expansion of an invadopodia/collagen-fiber ensemble upon drug addition (see Supplementary Movies 3 and 6 to 8). Drugs were added 15 min after starting the time-lapse (see colored lines), except in panel g, in which GM6001 was added at the beginning of the movie. Scale bars, 2 µm. h Quantification of the invadopodia elongation rate along collagen fibers in MDA-MB-231 cells treated with the indicated drugs. Data are presented as the mean from three independent experiments (DMSO, 8 experiments). n: cell number; (n): invadopodia number. Kruskal–Wallis and Mann–Whitney (Y27632 vs. H₂0) tests. i Displacement of invadopodia/collagen-fiber ensemble over time before and after laser-ablation in low-dose CytoD (100 nM, orange) and mock-treated cells (gray). Curves represent the mean of 29 (Mock) and 36 (CytoD) curves aligned at rupture time-point (t₀). n: number of cells analyzed from three independent experiments. Two-way ANOVA with Sidak’s multiple comparisons test for each time point. Error bars SEM, * P < 0.05, ** P < 0.01, **** P < 0.0001, ns not significant