BRAF and melanoma: This is because 1) in clinical trials on melanoma, only 12% of tumors with BRAF mutations were partially responsive to AZD6244 [97], 2) NSCLCs with KRAS mutations display heterozygous responses to MEK inhibitors, and 3) a minor proportion (21%) of patients having BRAF V600 mutation showed responses to the MEK inhibitor GSK1120212 [101, 102].