CXCR2 and esophageal squamous cell carcinoma: Yang et al. demonstrated that targeting tumor-derived CXCL1 or blocking the CXCL1-CXCR2 signaling pathway could restore the radiosensitivity of radioresistant esophageal squamous cell carcinoma (ESCC) xenografts in vivo, indicating the potential of CXCL1 as a predictive biomarker for radiosensitivity in ESCC9.