EGF and head and neck squamous cell carcinoma: We found blockade of EGF/EGFR axis reduced the expression of CCL2 in Cal27 cells, while suppression of CCL2/CCR2 axis decreased the expression of EGF in THP1 cells, suggesting that in HNSCC, the crosstalk between cancer cells and macrophages was also mediated by a positive feedback paracrine loop.