Rac2 promotes both experimental as well as spontaneous metastasis.

<p>(A) Experimental metastasis of B16 melanoma cells in WT and Rac2-/- mice (n = 5). B16 F10 melanoma cells (5×10⁵ cells) were injected through the tail vein, and after 15 days, the lungs were removed and the photographs were taken shown as upper panel in the figure. Lower panel shows mean number of tumor nodules visible on the surface of the lungs in WT and Rac2-/- mice. Surface tumor nodules in lungs were counted under dissecting microscope. Values are mean ± SEM (<i>n</i> = 5 or 6; <i>P</i><0.001; pair wise two-sided Student's <i>t</i> test). A marked suppression in the number of metastatic nodules was observed in Rac2-/- mice.(B) H&E-stained lung tissues demonstrating large macroscopic nodules (black arrows) were greatly increased in number and size in the WT vs. Rac2-/- mice, 15 d after B16 tumor cell injection. (C) Upper panel shows tumor mass of pancreatic tumors implanted orthotopically in WT and Rac2-/- mice. Panc02 (1×10⁶) cells were injected in the pancreas of WT and Rac2-/- mice (n = 10). Tumors were removed 30 days after tumor implantation. Values are mean ± SEM (<i>n</i> = 10; P<0.05; pair wise two-sided Student's <i>t</i> test). Bottom panel shows representative images of pancreatic tumors isolated from pancreas of WT and Rac2-/- mice. (D) Left panel shows macroscopic view of Panc02 metastatic mesenteric lymph nodes from WT and Rac2-/- mice. Right panel shows number of metastatic mesenteric lymph nodes/mesentery. Values are mean ± SEM (<i>n</i> = 5 or 6; P<0.001; pair wise two-sided Student's <i>t</i> test). The data are representative of three independent experiments performed.