{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Claudins are transmembrane proteins that form tight junctions, which regulates tissue permeability, paracellular transport, and signal transduction. There are 27 known members of the claudin family and claudin 18.2 isoform is a splice variant of claudin 18. Claudin 18.2 expression in normal tissues is confined to differentiated epithelial cells of the gastric mucosa. In cancer cells, claudin 18.2 is transcriptionally upregulated with the binding of cyclic AMP responsive element binding protein to the methylated claudin 18.2 promoter region. According to literature, overexpression of claudin 18.2 therefore, has been observed in several types of cancers, including gastric cancers."}]}]}