Fig 2: SKA1 remodels actin cytoskeleton via activating Cdc42. A, Pearson's correlation test was used to analyse the correlation between the expression level of SKA1 and Cdc42 according to TCGA database (R = .51, P < .01). B, Immunoblotting performed in PANC‐1 and Capan‐1 cells’ infectants to verify the proteins that regulate actin cytoskeleton. C, Cdc42‐GTP pull‐down and Western blot analyses of the activation state of Cdc42 expression and total expression of Cdc42 in the indicated cells. D and E, The application of ZCL278 resulted in a dose‐dependent decrease in Cdc42 activity, followed by inhibition of endogenous Arp2/3, N‐WASP. F, Cells were fixed and stained with rhodamine‐phalloidin to label filamentous actin following ZCL278 treatments. Results showed that ZCL278 inhibits microspike formation and stress fibres in PANC‐1 and Capan‐1 cells. White asterisks indicate the subcellular locations that normally show stress fibre distribution. White arrows point to the seemingly disruption Golgi organization. G, RhoA, RhoB, RhoC and Rac1/2/3 protein expression were detected, and only a total of Rac1/2/3 increase accompanied by SKA1 overexpression was observed. H, FAK, Talin and ɑ‐actinin levels increased with SKA1 expression in Capan‐1 cells, FAK, Paxillin and ɑ‐actinin levels decreased with SKA1 knockout in PANC‐1 cells. I, Proposed mechanistic scheme of SKA1 in promoting tumour progression in PDAC

Fig 3: Pharmacological blocking of Cdc42 inhibits pulmonary metastasis of HCC in vivo. a Left: Representative bioluminescence images of pulmonary metastasis from vehicle- or ZCL278-treated mice (n = 6/group) tail vein intravenously injected with HCC cells stably overexpressing ARHGEF37. Right: The statistical results of the luminescence signals for lung metastasis. b Representative images and quantitation of metastatic nodules in the lungs. Scale bars: 50 μm. c Kaplan–Meier survival curve of mice from experiments in (a) (n = 6/group). d The control or ARHGEF37-overexpressing GFP+-HCC cells were treated with vehicle or ZCL278 before injection through tail veins. Lungs were assayed at 4 and 24 hours after injection (n = 6). Representative lung section images at 4 and 24 hours after injection are shown. The GFP+-HCC cells were detected and quantified. Scale bars: 10 μm. Each value in panel a, b and d represents the mean ± SD of six mice/group. * P < 0.05; ** P < 0.01; *** P < 0.001; ns represents not significant

Fig 4: Inhibition of Cdc42 activity blocks the effects of ARHGEF37 on invasiveness. a Immunoblotting analysis of GTP-Cdc42, Cdc42, p-PAK1, and PAK1 levels in the indicated cells treated with vehicle or a Cdc42 specific inhibitor, ZCL278. b Representative immunofluorescence images and quantitation of ARHGEF37-transduced cells treated with vehicle or ZCL278 in endothelial adhesion assays. Scale bars: 50 μm. c Representative immunofluorescence images and quantitation of ARHGEF37-transduced cells treated with vehicle or ZCL278 in trans-endothelial migration assays. Scale bars: 50 μm. d The pericyte-endothelial interaction junctional protein N-cadherin was analyzed in a 2D co-culture with ARHGEF37-transduced tumor cells upon treatment with vehicle or ZCL278. Scale bars: 5 μm. e The pericyte-endothelial interaction junctional protein Cx43 was analyzed in a 2D co-culture with ARHGEF37-transduced cells tumor cells upon treating with vehicle or ZCL278. Scale bars: 5 μm. Data of panel a are derived from three independent experiments. Each error bar in panel b and c represents the mean ± SD of three independent experiments. * P < 0.05; ** P < 0.01; *** P < 0.001