Evidence that Rac1 activity is essential to maintain HRas
-induced tumor formation. Solid lines represent mice that were not administered tetracycline (Tet). Dotted lines represent mice injected with the same cell strain, but mice were given Tet in order to suppress dominant-negative expression. Tumors were measured weekly. When tumors reached a volume of approximately 0.5 cm3, mice were sacrificed and the tumors were removed for further analysis. The data are plotted using Kaplan-Meier analyses. (a) PH3MT-tTak-C1 (parent); N = 4 (- Tet), N = 4 (+ Tet) p > 0.1. (b) PH3MT-VC-C2 (vector control); N = 5 (- Tet), N = 6 (+ Tet) p > 0.1. (c) PH3MT-Rac1N17-C1; N = 7 (- Tet), N = 9 (+ Tet), p < 0.001. (d) PH3MT-Rac1N17-C2; N = 4 (- Tet), N = 6 (+ Tet), p > 0.1. (e & f) Western blots probed with myc (9E10) antibody to detect dominant-negative protein expression in two tumor-derived cell lines (Tumor 1 and Tumor 2) Both blots were probed with β-actin to verify loading.