CXCR4 and neoplasm: While silencing of microRNA-454 led to increased CXCL12 expression, macrophage recruitment via the CXCL12/CXCR4 axis, and a reduction in tumor size, the overexpression of microRNA-454 significantly reduced CXCL12 expression and increased tumor size, indicating that CXCL12 negatively impacts PDAC progression [208].