ERK can regulate SMAD function at various levels in TGF-β signaling, but we did not detect any effect of MEK inhibition on SMAD2 steady state or TGF-β-induced nuclear localization, or TGF-β-stimulated transcription of SPARC or VEGF in melanoma cells (Figures S5A and S5B). This evidence concerns the gene MAPK1 and melanoma.