Figure 4

Rac1-mediated invasion depends on a threshold of Rac1 expression. A) Rac1 siRNA-concentration dependence of cell invasion. SNB19 cells were transfected with the indicated Rac1 siRNA concentrations and invasion assays were performed as in Figure 3. The results shown represent the means +/− SEM of 4 independent experiments, performed in duplicate. Data were normalized to those of control cells. B) Rac1 siRNA-concentration dependence of Rac1 activation state. Cells were transfected with the indicated Rac1 siRNA concentrations and Rac activity was determined as in Figure 2B. The results shown represent the means +/− SEM of 5 independent experiments. C and D) Rac1 siRNA-concentration dependence of Rac1 expression. C) Representative western blot demonstrating siRNA-dependent depletion of Rac1. D) Quantification of western blots for experiments shown in A) and B). The results shown represent the means +/− SEM of 8 independent experiments. Data were normalized to those of control cells.