MX1 and breast cancer: In our working model shown in Figure 9, we propose that in AI-resistant MCF-7:5C breast cancer cells, the transcription factor IRF-7 which is a key regulator of IFNα, is dramatically upregulated and that increased IRF-7 expression in the resistant cells stimulates the production of IFNα which is then secreted from the cells and binds to the IFNAR1/2STAT1/STAT2/IRF-9 complex to induce the expression of ISGs (that is, IFITM1, PLSCR1, IFIT1, IFI21, OAS1, MX1, STAT, STAT2, IRF-7, IRF-9).