OCLN and cancer: As an epithelial marker, occludin is downregulated during EMT.70 Epigenetic silencing of occludin leads to metastasis of cancer cells via modulation of unique sets of apoptosis-associated genes.71 Moreover, its knockdown decreases TRAIL-induced cell death, thus conferring an important role of occludin in apoptosis.72 Indeed, occludin (and to a lesser extent claudin) interacts physically with Fas associated via death domain (FADD) and DISC when tight junctions are disrupted, a phenomenon allowing cell defence (an antibacterial strategy) by activating the extrinsic cell death signal.73,74