PLX4032 selectively inhibits phosphorylation of signaling targets in BRAFV600E-positive thyroid cells. A) Whole cell protein was collected from Nthy-ori 3–1 cells that were treated for 24 hours with 5 μM (+) or 10 μM (++) PLX4032. Protein samples (10 μg per lane) were subjected to SDS-PAGE followed by western blot analysis for MEK (46 kD), p-MEK (45 kD), MAPK (42/44 kD), p-MAPK (42/44 kD), mTOR (289 kD) and p-mTOR (289 kD). GAPDH (37 kD) was used as a loading control. Quantification of Western blots by densitometry was performed using ImageJ and bar graphs represent percent expression compared to the untreated. B) BCPAP cells were treated and collected, whole cell lysates resolved by SDS-PAGE and analyzed by western blot in the same way as Nthy-ori 3–1 cells in A.