Influence of formin inhibition on filopodia formation and actin distribution. (A) Illustration of the filopodia detection scheme, with a HeLa cell expressing lifeact-GFP. (B) An example of a HeLa cell expressing lifeact-GFP treated with 40 µM SMIFH2 for 1 h. (C) Using a scheme similar to that shown in Fig. 2 A, the distribution of a fluorescent signal of interest (in this case, lifeact-GFP) can be quantified. The segmented image of a cell is iteratively eroded, and at each step, the fluorescence signal along the image boundary is summed. This permits the plotting of fluorescence intensity as a function of distance to the cell center. (D) The number of filopodia detected per minute by ADAPT in the presence or absence of a formin inhibitor (**, P < 0.01). Each dot represents one cell (ncell = 10 in each population). Error bars represent standard error of the mean. (E) Cellular distribution of actin in control and SMIFH2-treated cells. Error bars represent 95% confidence intervals. Bars, 20 µM.
