Figure 6. Effects of sorafenib on the activation of B-Raf, C-Raf and MEK1/2, and expression of cell cycle regulatory proteins. (A) SK-N-AS and CHLA255 cells were treated with 5 µM sorafenib for 0, 1, 5, 15, 30 and 45 minutes. Then, total cell proteins were assayed for expression of phosphorylated B-Raf, C-Raf and MEK1/2 with specific antibodies. (B) Sorafenib suppressed tumor growth of neuroblastoma in a mice xenograft model. SK-N-AS neuroblastoma tumor cells (5 x 10⁶ per animal) were impanted s.c. in female NOD/SCID/IL2Rγ null mice (n = 5). Sorafenib and the vehicle were administered at 60 mg/kg, once daily by oral gavage.