(A) Endogenous R-Ras was knocked down by R-Ras shRNA. Cells were stimulated with VEGF at the indicated doses for 15 min. (B) Cells were stimulated with or without 50 ng/ml VEGF. The level of phospho-p38MAPK was quantified, normalized to total p38MAPK, and presented as relative values compared with the VEGF-stimulated control cells. NC, negative control shRNA. Error bars, SEM. n=3. *p<0.05, ns: non-significant difference.