Figure 7. Effects of caveolin-1 on Rho-GTPases in MDA-MB-231 cells.

(A) Kinetics of Rac1 activation upon spreading. MDA-MB-231 cells, stably transduced with shRNA either targeting Luciferase (sh-ctrl) or caveolin-1 (sh-cav1), were allowed to attach/spread onto fibronectin-coated plates (2 µg/ml) for different periods of time. Cell extracts were prepared and Rac1-GTP levels were measured by using the GST-PBD pull down assay, as indicated in the Materials and Methods. Rac1-GTP levels were normalized to total Rac1 by scanning densitometry. Data were averaged from three independent experiments (mean ± SEM). *P<0.01; **P<0.05. (B) RhoA activity was measured by the GST-RBD pull down assay in cells induced to spread onto fibronectin at different time points, as in (A). Data were averaged from three independent experiments (mean ± SEM).