Therefore, we confirmed IκBζ protein expression by immunohistochemistry (IHC) on formalin-fixed, paraffin-embedded (FFPE) samples from primary and metastatic melanoma, using a home-made antibody against human IκBζ, which we validated beforehand (Supplementary Figs. S1d, e). This evidence concerns the gene NFKBIZ and metastatic melanoma.