RhoG and Rac1 contribute to glioblastoma cell clonogenicity. A) Colony formation assay. SNB19 cells were transfected with siRNAs (10 nM) directed against luciferase (control), RhoG or Rac1. Colony formation assays were performed as described in Materials and Methods. The results shown represent the means +/− SEM of 4 independent experiments (each performed in quadruplet dishes) for the RhoG and 3 independent experiments for the Rac1 knock-downs (p < 0.001, two-tailed t test). B) Western blot demonstrating depletion of RhoG and Rac1.