Fig. 5

Dynamics of unconstrained filopodia Inhibition of myosin II or formins interfered with growth of unconstrained filopodia. a A cell expressing GFP-myosin X and F-Tractin-tdTomato representative of those used in experiments assessing filopodia growth. The filopodium attached to the laser trapped fibronectin-coated bead is indicated by the red arrowhead. Such filopodia were excluded from the score. Scale bar 2 μm. b Histograms showing the probability distribution of growth/retraction velocities (nm/s) of unconstrained filopodia in HeLa-JW cells, measured in the same experiments as those assessing growth of filopodia attached to the fibronectin-coated beads. Positive values of the velocities correspond to growth, and negative—to retraction of filopodia. Probabilities represent the mean fractions of time, during which the velocity value belonged to a given interval with a width 15 nm/s. The numbers of assessed filopodia (with number of cells in parenthesis) were 24 (5), 24 (4), 43 (6), 24 (5), and 42 (8) for (from top to bottom) control (gray), myosin IIA HC siRNA knockdown (blue), S-nitro-blebbistatin (orange), Y-27632 (green), and SMIFH2 (purple) treatments, respectively