POLI and esophageal squamous cell carcinoma: Then, ESCC cells were exposed to X-ray irradiation and given either ectopic expression of POLI (i.e. TE-1 POLI oe vs TE-1 NC) or specific knockdown endogenous POLI (i.e. KYSE-150-shPOLI vs KYSE-150-shNC).