CLDN2 and neoplasm: Besides, researches on the association between CLDN2 and cancer has been steadily increasing (Piontek et al., 2020), with a growing evidence elucidating its involvement in tumor growth, metastasis, and metabolism (Eguchi et al., 2021; Hirota et al., 2021; Tabaries et al., 2021; Wei et al., 2021).