CXCR4 and neoplasm: Furthermore, tumor exoRNAs can activate lung epithelial cell TLR3 to recruit neutrophils due to the expression of chemokine receptors (CXCR1, CXCR2, CXCR4, andCCR2) being higher in tumor-bearing Tlr3−/− mice, consequently inducing lung premetastatic niche formation [31].