A) Protein expression of phospho-ERK (pERK), total ERK (tERK), phospho-MEK (pMEK), total MEK (tMEK), phospho-PTEN (pPTEN), total PTEN (PTEN), phospho-AKT (pAKT), and total AKT (AKT) in melanoma cell lines with the BRAF V600E mutation (1205Lu, 451Lu), the K601E mutation (WM3130), the D594G mutation (WM3629) and the G469E mutation (WM3670). B) The G469E and D594G mutated melanoma cells are resistant to MEK inhibition. Cells were treated with increasing concentrations of a MEK inhibitor (U0126) (3nM – 10 μM) for 72 hrs and cell proliferation was measured by the MTT assay. C). D594G mutated melanoma cells are highly sensitive to the CRAF inhibitor sorafenib. Cells were treated with increasing concentrations of sorafenib for 72 hrs, cell proliferation was measured as in B). Data shows the mean of 3 independent experiments +/- S.E. mean.