Higher levels of U-ISGF3 in SCLC cell lines correlated with increased resistance to DNA damage, and when we knocked STAT1 and IRF9 down to reduce the levels of U-ISGF3, normal BJ fibroblasts and the resistant SCLC cell line H196 became more sensitive to DNA damage induced by doxorubicin. Here, IRF9 is linked to small cell lung carcinoma.