CXCL1 and esophageal squamous cell carcinoma: In ESCC, metformin-mediated activation of AMPK resulted in CXCL1 downregulation, leading to an overall decrease in PMN-MDSC infiltration while in HNSCC, metformin was found to inhibit CXCL1 and mTOR activation, resulting in increased NK cell infiltration and cytotoxicity [213].