NRAS and melanoma: Since SWATH-MS protein phenotyping did not discriminate the melanoma cell lines based on mutational genotype, we investigated this by screening for response to the MEKi selumetinib (AZD6244) which has been shown to be effective in controlling downstream ERK phosphorylation in BRAF and NRAS mutant tumors (Fig. 1c).27 We observed an association with the unsupervised grouping seen in Fig. 1a, b, in that these 6 cell lines were the most sensitive to 2 μM selumetinib after 10 days (average 26 ± 12% viable cells).