Three markers involved in immune regulation, programmed cell death-ligand 1 (PD-L1), C-X-C chemokine receptor type 4 (CXCR4), and cyclooxygenase-2 (COX-2), have been studied for their prognostic implications in ESCC (Tables 1, 7). The gene discussed is CXCR4; the disease is esophageal squamous cell carcinoma.