STAT2 and malignant colon neoplasm: Upregulation of ISG expression in HSF could be linked to IRF1-stimulated p53 activity, as demonstrated in the human colon cancer cell line HCT116 [39], and/or p53 ISGylation that forms a positive feedback loop for its transcriptional activation [40], and/or increased ISGF3 production dependent on IRF9, STAT1 and STAT2 intracellular amounts.