No changes in MEK1/2 expression were detected in either cell line regardless of drug treatment, but phosphorylation of MEK1/2 was dramatically reduced after treatment with BRAF inhibitor in WT and KRAS G13D, but not in NRAS Q61K A375 cells, indicating a differential impact on MEK signaling between the two RAS mutant melanoma models. This evidence concerns the gene KRAS and melanoma.