RhoA activated by vincristine. A and B. Cells were starved in serum-free RPMI1640 for 24 h, and then exposed to vincristine. After vincristine treatment, the cells were harvested to evaluate RhoA activity by rhotekin-based pull-down assay. RhoA in pull-down samples (active RhoA) and in total lysates (total RhoA) were detected by Western blotting using an anti-RhoA antibody. A, time-course; B, concentration-response at 15 min. The blots in (A) and (B) are representative of three independent experiments. The blots were quantified by densitometry, and the results were expressed as ratio relative to the values obtained in non-treated control cells (0 min or 0 μM). The graphs in (A) and (B) show means ± S.E. of three independent experiments. *, P < 0.05 versus control.