Background：

This gene encodes a member of the claudin family. Claudins are integral membrane proteins and components of tight junction strands. Tight junction strands serve as a physical barrier to prevent solutes and water from passing freely through the paracellular space between epithelial or endothelial cell sheets， and also play critical roles in maintaining cell polarity and signal transductions. Differential expression of this gene has been observed in different types of malignancies， including breast cancer， ovarian cancer， hepatocellular carcinomas， urinary tumors， prostate cancer， lung cancer， head and neck cancers， thyroid carcinomas， etc.. Alternatively spliced transcript variants encoding different isoforms have been found.