In addition, considering higher PD-L1 expression being described in HLA-DR+ melanoma cell lines and that HLA-DR mediated signaling increases the expression of PD-L1 in melanoma cells (13, 39), we compared the expression of PD-L1 between HLA-DR- and HLA-DR+ melanoma cells and could observe significant higher expression levels in the HLA-DR+ melanoma cells (Wilcoxon rank sum test, fdr corrected, p-adj < 1x e-16,Figure 4C). This evidence concerns the gene CD274 and melanoma.