BrdU and TUNEL analysis after sorafenib treatment. Sorafenib inhibited the proliferation of thyroid carcinoma derived cell lines and induced apoptosis in the cell line harbouring the BRAFV600E mutation (8505C). (a) Proliferation analysis by BrdU assay after treatment with sorafenib at a dose of 4 uM for 48 hours: all treated cell lines showed a significant (*p < 0.05) decrease in the percentage of cells incorporating BrdU in comparison to the vehicle (DMSO); (e, f) Representative photos of 8505C cell line showing decreased incorporation of BrdU in treated cells when compared with the DMSO control. (b) Apoptosis analysis by TUNEL assay after treatment with sorafenib at a dose of 4 uM for 48 hours. The cell line harbouring BRAFV600E mutation (8505C) showed a significant increase (*p < 0.05) in the levels of apoptotic cells after sorafenib treatment in comparison to cell lines harbouring wild-type BRAF (TPC1, C643). (g, h, i, j) Representative photos of 8505C cell line showing increased TUNEL labelling in treated cells when compared with the DMSO control. DAPI: counter stain to detect nuclei in FITC-stained cells in TUNEL and BrdU assays (c, d- phase contrast 20×; e, f, g, h, i, j, 40×). All values presented are the mean of at least three independent experiments.