ISG15 and breast cancer: Treatment of breast cancer cell lines (including BT-474 and MCF7) with DNA methyltransferase (5-azacitidine) led to activation of DDX58, IFI27, IFI6, IFIH1, ISG15, MX1, OAS3, UBE2L6, XAF1 (9 of the 19 PUGs), and other genes [30].