FIGURE 5:

The S1P–S1PR2 pathway regulates filamin accumulation. (A) Confocal microscopic immunofluorescence images of filamin (red) in normal MDCK cells or S1PR2-knockdown MDCK cells at the interface with MDCK-pTR GFP-RasV12 cells. Arrowheads indicate filamin accumulation. Left, bottom, mixture of normal and RasV12 cells incubated with JTE013. Scale bars, 10 μm. (B) Quantification of the filamin accumulation by confocal microscopic analyses. Several confocal xy-section images were examined for the presence of filamin accumulation. Data are mean ± SD from three independent experiments. Values are expressed as a ratio relative to MDCK cells: pTR-RasV12 = 50:1 (JTE013 –). *p = 8.8 × 10⁻⁵, **p = 0.016, ***p = 0.0019. (C) Model for the functional role of S1P–S1PR2 in the interaction between normal and transformed epithelial cells. 1) S1P from the outer environment binds to S1PR2 in the surrounding normal cells, which 2) leads to activation of Rho; then 3) Rho–Rho kinase mediates filamin accumulation, resulting in the apical extrusion of the neighboring transformed cells.