NRAS and melanoma: The elongated di-retro-peptide RDP22 exhibited highly increased antitumor activity with a cancer-specificity of more than 1000-fold for cell lines of primary melanoma (Sbcl-2, NRAS mutated) and more than 500-fold for melanoma metastases (WM164, BRAF mutated) at a peptide concentration of 20 μM as compared to normal melanocytes [14].