ERAP1 and metastatic melanoma: Interestingly, many of the upregulated proteins in the USP18-dependent interferome overlap with a subset of factors recently identified to be upregulated in metastatic melanoma responders to ICB.43 In particular, USP18 regulates the expression and/or ISGylation status of PSME1, PSMB9, PSMB10, B2M, TAPBP, TAP1, TAP2, CBR3, STAT1, IFIT1, GBP1, GBP2, ERAP1 and MAGE, all linked to better responses to ICB therapy with PD1 inhibitors (Table S2).