R-Ras Regulates Migration through an Interaction with Filamin A in Melanoma Cells
Figure 4
The association between R-Ras and FLNa enhances integrin activation.
A) M2 cells express a subset of integrins on their surface. FACS analysis of a subset of integrins expressed on the surface of M2 cells. M2 cells express α5 and β1 subunits on their surface but not αvβ3. B) Forced expression of activated R-Ras promotes integrin activation in M2 cells as determined by the 3Fn-(9–11) activation assay. M2 (FLNa-) cells were transiently transfected with expression vectors encoding GFP as transfection reporter and FLNa, constitutively active R-Ras G38V alone or ±FLNa or FLNaΔ3. Cells were harvested and analyzed by two-color FACS for transfected cells and 3FN-(9–11) binding. Shown on the Y-Axis is mean activation index ±S.E. of three independent experiments. Constitutively expressed active R-Ras G38V and FLNa increased the activation index more than R-Ras alone. FLNaΔ3 did not block R-Ras-mediated activation compared with controls. Statistically significant differences are reported in the graph as P values (Student's t-test), *, P<0.05 **, P<0.04 C) Western blot of R-Ras levels when transiently transfected with R-Ras G38V. Tubulin was used as a loading control. Data represent at least 3 independent experiments.