For example, Holzgruber et al. showed that treating human melanoma cell lines A2058 and A375 with type I interferons (IFN-α or IFN-β) significantly induced PDCD1 expression, both at the mRNA and surface protein levels, via the IFNAR-JAK-STAT1/2-IRF9 signaling pathway. This evidence concerns the gene IRF9 and melanoma.