CLDN2 and irritable bowel syndrome: Increased production of IL-6, a cytokine known to increase TJ permeability in IBD (Suzuki et al., 2011), is reported to enhance the expression of Cdx-2 via PI3K pathway that in turn transcriptionally activates Cldn-2 and consequently increases TJ permeability for cation molecules (Suzuki et al., 2011).