CLDN1 and esophageal squamous cell carcinoma: Given that CLDN1 is mostly found in the nucleus of esophageal squamous cell carcinoma (ESCC) and has been shown to be abnormally elevated, CLDN1 promotes ESCC growth and metastasis by upregulating the expression of ULK1 via the AMPK/STAT1 signaling pathway (14).