Fibrosis occurs due to abnormal damage repair and wound healing.[79, 80] It is linked to many human diseases, including liver cirrhosis, renal fibrosis, pulmonary fibrosis, epithelial tumors, and fibrotic eye diseases.[81, 82, 83, 84, 85] The most important characteristic of fibrotic diseases is the epithelial–mesenchymal transition (EMT), in which activated transcription factors including snail 1/2, Twist, ZEB1/2 and others repress expression of E‐cadherin, ZO‐1 and other epithelial marker genes. The gene discussed is TJP1; the disease is cirrhosis of liver.