IL1R2 and carcinoma: BMI1 is a core component of polycomb repressive complex 1 (PRC1), which mediates gene silencing via monoubiquitination of histone H2A and plays a key role in stem cell and TIC self‐renewal.17 BMI1 is overexpressed in breast and other carcinomas, and is associated with poor outcomes.18 Our GSEA analysis results showed a significant enrichment of the BMI1 target genes in SUM159‐IL1R2/‐icd‐IL1R2 cells (Figure 3A).