Map3k1 is amplified in a subset of human desmoplastic melanomas (Shain et al, 2015a) and was previously linked to melanoma progression by two, independent transposon-mediated mutagenesis screens conducted in the Tyr::CreER(T2) BrafCA model (Ni et al, 2013; Mann et al, 2015). This evidence concerns the gene MAP3K1 and melanoma.