Here, we found that IL1R2 intracellular domain (icd‐IL1R2) could bind to the deubiquitinase USP15 at the UBL2 domain and promoted USP15 deubiquitinase activity on BMI1 protein deubiquitination at K81 and finally increased BMI1 stability in BC cellular nucleus. The gene discussed is USP15; the disease is breast cancer.