UBE2S and intraepithelial neoplasia: The present investigation was aimed to examine ubiquitin‐conjugating enzyme E2S (UBE2S), hypoxia‐inducible factor (HIF)‐1α, and factor forkhead box M1 (FOXM1) levels in esophageal squamous cell carcinoma (ESCC) and esophageal low‐grade intraepithelial neoplasia (LIN), high‐grade intraepithelial neoplasia (HIN).