NRAS and melanoma: SK-Mel-2 melanoma cells have been reported to contain either an NRASQ61R [9, 17] or a KRASQ61R [11] mutation, but sequencing of the amplified exons 3 of NRAS and KRAS in the cells used in our experiments confirmed that the mutation is NRASQ61R, not KRASQ61R (S1 Fig).