MAP2K1 and melanoma: Finally, the authors discussed the heterogeneity exhibited by melanomas without BRAF mutations, in which a subgroup having very similar clinical and morphological characteristics as those observed in melanomas with BRAF mutation was observed, suggesting the possibility that they are biologically related and, perhaps, alternative genes acting immediately downstream of BRAF, such as MEK1 and MEK2 could be candidates for target therapy in this context [26].