Anti-tumor activities of RO5126766 and FDG-PET imaging results in human colon carcinoma xenografts in Balb nu/nu mice. Mice bearing (a) COLO320DM (wt) (b) HCT116 (K-ras) and (c) COLO205 (B-raf) mutant tumor xenografts were orally administered once daily for 9 days with vehicle, 0.1, 0.3 or 1.0 mg/kg of RO5126766. The tumor sizes are mean ± SD (n = 10). Error bars = standard error, **p < 0.01. FDG-PET imaging was performed at baseline (day 0) and day 3 after the treatment with RO5126766 in (d) COLO320DM (wt) (only high dose) (e) HCT116 (K-ras) and (f) COLO205 (B-raf). The SUVmax values are mean ± SE (n = 6). *p < 0.05, **p < 0.01. Representative PET images (coronal sections) of (g) COLO320DM (wt) (h) HCT116 (K-ras) and (i) COLO205 (B-raf) tumors on days 0 (baseline) and 3 of the treatment with RO5126766, 1 mg/kg. Tumors are shown in the boxed areas, twofold magnifications. All images scaled to the same color scale.