ARHGAP17 KO validation and spontaneous invadopodia formation in ARHGAP17 KD cells. (A) Representative Western blot showing loss of ARHGAP17 protein in SUM159 ARHGAP17 KO cells using two different gRNA targets. Molecular weights are indicated in kD. (B) Percentage of cells with invadopodia after treatment with PDBu for 30 min. Results are expressed as mean ± SEM of three independent experiments in which at least 200 cells per condition per experiment were counted. Significance was tested with a two-tailed t test: **, P < 0.01. (C) Percentage of non-treated SUM159 cells with invadopodia. Results are expressed as mean ± SEM of three independent experiments in which at least 200 cells per condition per experiment were counted. Significance was tested with a two-tailed t test: **, P < 0.01. (D) Representative micrographs of ARHGAP17 KD and Rescue with shRNA resistant myc-ARHGAP17 in SUM159 cells. F-actin and cortactin staining were used as markers for invadopodia while myc staining was used to visualize myc-ARHGAP17. Arrowheads highlight invadopodia clusters. The zoomed regions are marked by a dashed line (scale bar, 20 μm). Source data are available for this figure: SourceData FS1.