ERK1/2 activation is B- and CRAF-dependent in GHM cells. (A) Fold change of ARAB, BRAF and CRAF mRNA after silencing with specific siRNAs in HoMel-A1 and HoMel-L1 cells as compared to scrambled control siRNA (siNeg). Fold changes are expressed as a range, with the standard deviation of the ΔΔCT value incorporated into the fold change calculation. (B, D) Contribution of individual RAF kinases to ERK1/2 activation in HoMel-A1 and HoMel-L1 cells after silencing with specific siRNAs or scrambled control siRNA as assessed by Western blot analysis. Representative images of one of three independent experiments are shown. (C, E) Quantification of total ERK1/2-normalized ARAF, BRAF, CRAF and P-ERK1/2 protein levels in individual silencings. Shown are the mean ± s.e. of three independent experiments.