Figure 7. Activity of small-molecule inhibitors of the MAPK pathway in BRAF^V600E-induced thyroid tumors.

Mice were pretreated for 1 week with dox and then either fed with PLX4720 or vehicle chow for 2 weeks or given PD0325901 (12.5 mg/kg every 12 hours) or vehicle for 6 days in the continued presence of dox. (A) Ki67 index of thyroid sections from mice treated with or without the indicated drug. The proliferative index was significantly decreased by both compounds. ***P < 0.001. (B) Serum TSH levels of mice treated with or without the indicated compounds. TSH levels were significantly lower in mice treated with PD0325901. **P < 0.01. (C) Expression levels of the indicated genes normalized to β-actin as determined by qRT-PCR in the indicated conditions. Gray bars indicate expression levels in mice not treated with dox. The number of animals per group is specified in the graph. Data are presented as the mean ± SEM.