PDCD1 and melanoma: Gene expression analysis of the six PD1 PROGs with intrinsic IFNγ signaling versus the remaining 15 PD1 PROG melanoma cell lines (minus the JAK2-mutant SCC16-0016 PD1 PROG) confirmed higher transcript expression of IFNγ-regulated transcription factors (IRF1/4), immune inhibitory ligands PDCD1LG2, LGALS9 (PD-L2 and galectin 9, respectively) and MHC-I antigen presentation effectors (TAP1, TAPBP, HLA-B, HLA-C) in the PD1 PROGs with intrinsic IFNγ activity (FDR-adjusted p-value < 0.05; Supplementary Data S2).