ISG15 and cancer: In this regard, a panel of 8 ISGs (STAT1, MX1, ISG15, OAS1, IFIT1, IFIT3, IFI44, and USP18), constituting the “IFN-related DNA damage resistance signature” (IRDS), was associated with cancer cell-intrinsic resistance to various DNA damaging agents (such as anthracyclines, taxanes, cyclophosphamide, methotrexate, and 5-fluorouracil) and radiation therapy, as well as with poor prognosis in a variety of malignancies, including breast cancer and glioblastoma [126,127].