CXCR4 and breast carcinoma: Accumulated aged neutrophils have been reported to accelerate vascular damage and induce tumor progression by promoting lung metastasis in breast cancer through the formation of vital mitochondria‐dependent NETs.[43] Here, we observed that CXCR4+ neutrophils within tumors expressed significantly higher levels of PD‐L1 and Siglec F than the corresponding CXCR4− neutrophils.