Transient Cdc42 depletion reduces MDA-MB-231 cell metastasis in vivo. SCID mice were injected in the tail vein with MDA-MB-231 cells transfected with a control siRNA (Control) or with Cdc42-1 and Cdc42-2 siRNAs. (A) Representative images of whole lung sections stained with hematoxylin and eosin. Bar, 20 mm. (B) Quantification of the percentage of lung areas positive for foci. Values are means ± SEM (error bars); *, P < 0.05; ***, P < 0.001; determined by a two-way ANOVA test.