Fig. 5

A Syk inhibitor blocks podoplanin-expressing melanoma tumour cell and platelet aggregation in vitro and pulmonary metastasis in vivo. (A). Syk inhibitor (R406)- or DMSO-pretreated platelets were incubated with PDPN + cells, and the mean fluorescence intensity (MFI) of each group was measured by flow cytometry. The MFI of platelets without CellTracker labelling with PDPN + cells was used as a control. The MFI of each group is shown. (B). Fold changes in mean fluorescence intensity compared with the control were determined. Data are means ± SEMs (n = 3) (**P < 0.01) (C). Representative immunofluorescence images of PDPN + tumour cells mixed with platelets pretreated with DMSO or R406 in vitro. Scale bar = 10 μm. (D). Western blot profiles showing phospho-syk expression after tumour cells were mixed with platelets. (E). Images of metastatic lung nodules from tumour cell-inoculated mice treated with 30 mg/kg R406 or DMSO. (F). The number of metastatic nodules on the surface of the lung was analysed. Data shown are the means ± SEMs (n = 3). (**P < 0.01) (***P < 0.001)