MITF and melanoma: We also observed MITF and target gene upregulation in BrafV600E mouse melanoma allografts in syngeneic mice treated with an MEK inhibitor, as well as in human BRAFV600E melanoma xenografts grown in mice treated with either a BRAF inhibitor or an MEK inhibitor, and again this correlated with downregulation of DUSP6 expression (Figures 1B and S1B).