TRIM21 and breast cancer: STAMBPL1 has been implicated in various cancer types by targeting different proteins.[18] In prostate cancer, targeting the STAMBPL1 triggers apoptosis by promoting XIAP degradation.[19] In breast cancer, STAMBPL1 contributes to cisplatin resistance by stabilizing MKP‐1 expression.[20] Meanwhile, STAMBPL1 is also reported to be essential in the EMT process in lung and breast carcinomas.[21] Here, it is demonstrated that STAMBL1/TRIM21 balances the level of AXL ubiquitination and thereby determines the expression of mesenchymal genes and immune evasion‐related genes.