TNF and melanoma: These results are the first to implicate activation of NF-κB in the expression of PD-L1 in melanoma but are consistent with suggestions from previous studies on dermal fibroblasts and cell lines taken from patients with myelodysplastic syndromes where NF-κB was shown to be involved in TNF-α and IFN-γ inducible expression of PD-L1.