Figure 6: Filamin acts as a key mediator in the interaction between normal and transformed epithelial cells.

(a) Immunofluorescence images of filamin (green) and vimentin (red). Asterisks indicate the Src-transformed cell surrounded by normal cells. Arrows indicate colocalization of filamin and vimentin in the neighbouring normal cells at the interface with the Src-transformed cell. (b) Quantification of vimentin accumulation in filamin A-knockdown cells at the interface with Src-transformed cells. Representative images were shown on the right. Values are expressed as a ratio relative to tet (−). Data are mean±s.e. from three independent experiments. *P=0.0020 (Student’s t-test). (c) Quantification of filamin accumulation in vimentin-knockdown cells at the interface with Src-transformed cells. Data are mean±s.e. from three independent experiments. Values are expressed as a ratio relative to tet (−). (d) Immunofluorescence images of PKC-ε (red) in the mix culture of MDCK pTR-filamin shRNA1 and ts-Src MDCK cells (green). Filamin shRNA1 expression was not induced (upper panels) or induced by tetracycline (lower panels). Arrows indicate the accumulation of PKC-ε in the surrounding cells at the interface with ts-Src MDCK cells. (e) Immunofluorescence images of phosphorylated vimentin (p-Ser38) in the mix culture of MDCK GFP-vimentin and ts-Src MDCK cells. Arrows indicate colocalization of phosphorylated-vimentin (white) and accumulated GFP-vimentin at the interface with Src-transformed cells (red). v-Src activation was induced at 35 °C (upper panels) or not induced at 40.5 °C (lower panels). Scale bars, 10 μm (a,b,d,e). (f) Effect of BIM-I on apical extrusion of Src-transformed cells. Data are mean±s.e. from three independent experiments. *P=0.0078 (Student’s t-test). (g) Effect of BIM-I on vimentin accumulation at the interface with Src-transformed cells. Data are mean±s.e. from two independent experiments. Values are expressed as a ratio relative to dimethyl sulphoxide (DMSO). *P=0.0037 (Student’s t-test). (h) Effect of BIM-I on filamin accumulation in the surrounding normal cells at the interface with Src-transformed cells. Data are mean±s.e. from two independent experiments.