TLR4 and breast cancer: NETs can activate cancer cell Toll-like receptor 4 (TLR4) through neutrophil elastase release, upregulating PGC-1α to promote mitochondrial biogenesis and tumor growth.408 Tumor-associated senescent neutrophils (Naged, CXCR4+CD62Llow) form unique mitochondria-dependent NETs to facilitate breast cancer lung metastasis.