For instance, PRMT1 promotes breast cancer metastasis,[22] epithelial‐mesenchymal‐transition in non‐small cell lung cancer,[23] and multiple myeloma tumorigenesis.[24] Besides, PRMT1 promotes the maintenance of AML harboring FMS‐like receptor tyrosine kinase‐3 internal tandem duplication (FLT3‐ITD) mutation via catalyzing methylation of FLT3‐ITD at arginine residues 972/973 (R972/973).[25] Furthermore, PRMT1 maintains the properties of tumor‐initiating cells in esophageal squamous cell carcinoma.[26] However, the critical role of PRMT1 in maintaining CML LSCs remains elusive. Here, FLT3 is linked to breast cancer.