USP15 and neoplasm: Under IL1β induction, the intracellular domain of IL1R2 could form a complex with ubiquitin‐specific protease 15 (USP15) and enhance USP15 activity, which then induces the deubiquitination and protein stabilization of BMI1, a polycomb group repressor essential for stem cell self‐renewal and tumor progression,13 and intrinsically regulates BTIC self‐renewal and BC cell proliferation and invasion.