Fig. 8

Force transmission and weakening of matrix counter-resistance by collagenolytic invadopodia. a Still image from a representative time-lapse sequence of Tks5^GFP-expressing MDA-MB-231 cells (green) embedded in a 3D-collagen gel (magenta). The nucleus is located at the cell rear. Tks5-positive invadopodia form ahead of the nucleus at the level of the advancing invasive protrusion. The right panel shows a gallery of non-consecutive frames (time in h:min) from the time-lapse sequence (see Supplementary Movies 9–10). The bottom row shows a zoom-in of the boxed region for the GFP channel. Tks5^GFP-positive structures form in association with constricting collagen fibers and expand in size during cell penetration. The cell contour is shown with a dashed line. * nucleus position based on the absence of a GFP signal. b Same as in a for GM6001-treated cells (time in hr:min, see Supplementary Movie 11). The expansion of Tks5^GFP-positive structures forming in association with constricting collagen fibers (arrowheads) is reduced as compared to the control situation, which prevents cell transmigration into the ECM. The cell contour is shown with a dashed line. * nucleus position. Scale bars, 10 µm; 5 µm (zoom-in). c Tks5^GFP-expressing cells were plated on cross-linked collagen (4% PFA, magenta) and analyzed by time-lapse microscopy. The gallery shows non-consecutive frames from a representative movie obtained from three independent experiments (time in h:min, see Supplementary Movie 12). The rigid collagen network is shown in the inverted images in the bottom row (pseudocolored blue). The cell contour is shown with a dashed line. Scale bars: 10 µm. d Kymograph analysis. Scale bar: 2 µm. e Elongation rate of invadopodia in cells plated on cross-linked collagen. Data are presented as the mean from three independent experiments. n: cell number; (n): invadopodia number. Mann–Whitney test. Error bars SEM, **** P < 0.0001