ISG15 and cancer: Surprisingly, both IFNα/β receptor subunits (IFNAR1 and IFNAR2) showed modest up-regulation (1.47 ± SD 0.165 and 1.84 ± SD 0.93 respectively) across all conditions; however, significant up-regulation of downstream targets was observed in cancer cells isolated only from syngeneic tumors including IRF transcription factors (Irf1, Irf2, Irf4, Irf7, Irf8, Irf9) as well as interferon target genes (Ifi27, Ifi35, Ifit1, Ifit3, Ifitm1, Ifitm3, Isg15, Isg20).