CLDN11 (claudin 11) is a tight junction protein that plays crucial roles in maintaining intercellular barrier integrity and regulating cellular functions across multiple tissues. The protein functions primarily through calcium-independent cell-cell adhesion and tight junction formation 1. In cancer biology, CLDN11 exhibits complex roles depending on cellular context. It acts as a tumor suppressor in nasopharyngeal carcinoma, where hypermethylation-mediated silencing promotes cell migration through interactions with tubulins TUBA1B and TUBB3, blocking tubulin polymerization 2. Conversely, CLDN11 promotes gastric cancer metastasis when secreted by CXCR7-positive fibroblasts via AKT pathway activation 3 and serves as a lymph node metastasis marker along with CCL21 4. In reproductive biology, CLDN11 regulates granulosa cell proliferation in polycystic ovary syndrome through PI3K-AKT signaling pathway activation, controlling CCND1 and PCNA expression 5. The protein's stability is regulated by IGF2BP3-mediated mRNA binding, which can be disrupted by TNF-α, leading to increased intestinal permeability in obesity-related severe acute pancreatitis 1. These findings highlight CLDN11's multifaceted roles in barrier function, cancer progression, and reproductive health.