MAP2K1 and melanoma: For the present study, we have chosen two BRAFV600 melanoma cell lines that differed in the activity of the BRAF/MEK/ERK pathway after they developed resistance to trametinib (TRA), 29_TRAR (p-MEK1/2low/p-ERK1/2low) and 21_TRAR (p-MEK1/2high/p-ERK1/2high).