We observed the same result when we compared patients with ER+ BC with those with ER– BC and BC cell lines from the Cancer Cell Line Encyclopedia (CCLE), which showed enrichment of the IFN and APM signatures in ER– BC compared with ER+ BC (Supplemental Figure 1, A and B; supplemental material available online with this article; https://doi.org/10.1172/JCI193153DS1). Here, IFNA1 is linked to cancer.