Figure 2.

Disrupting the RAS-PI3K Interaction Impairs RAC1 Activation and Reduces Tumor Growth

(A) Parental H1975 cells and H1975 cells expressing Pik3ca^WT or Pik3ca^MUT were starved overnight and stimulated with EGF (10 ng/mL) for the indicated times. Protein extracts were subjected to a RAC1 activation assay. One representative experiment from three is shown.

(B) Quantification of western blot in (C). The ratio of RAC1-GTP to total RAC1 is shown, normalized to the value at time 0.

(C and D) PC9 (C) and H1975 (D) parental cell lines and cells expressing either Pik3ca^WT or Pik3ca^MUT were injected into the flanks of nude mice (50,000 cells per mouse). The cells also contain a luciferase-expressing vector. Cells were allowed to grow, and tumor burden was measured by bioluminescence emission for the length of the experiment.

(E and F) PC9 (E) and H1975 (F) parental cell lines and cells expressing either a wild-type RAC1 or a dominant-negative version (RAC1^N17) were injected into the flanks of nude mice (50,000 cells per mouse). The cells also contain a luciferase-expressing vector. Cells were allowed to grow, and tumor burden was measured by bioluminescence emission for the length of the experiment.

Means of three replicates are shown (C–F).