USP18 and neoplasm: We assessed USP18 mRNA and protein levels in B16 tumor cells after IFN-α or IFN-γ stimulation and found that IFN-γ was a more potent inducer than IFN-α for USP18 expression (Figure 1A and B), as well as Stat1 phosphorylation, which is IFN-γ signaling downstream gene (Figure 1B).