BRAF and melanoma: Thus the BRAF V600E substitution is observed at twice the frequency of NRAS Q61 substitutions in melanoma—despite the fact that oncogenic mutations at NRAS Q61 likely arise at a higher frequency, both because there are more oncogenic mutations available (Q61K, Q61L, and Q61R, versus V600E), and because one of those mutations relies on the more frequent transition process.