OCLN and carcinoma: In this line, downregulation or loss of function of proteins involved in epithelial homeostasis such as tight junction components [claudins, occludins, ZO‐1 (zonula occludens‐1)] is frequently observed in several carcinomas (Steinestel et al., 2014; Zeisberg and Neilson, 2009), whereas the expression shift from epithelial keratins to mesenchymal vimentin, required for cell migration and invasion, is also commonly assessed in diverse types of tumors (Sarrio et al., 2008; Satelli and Li, 2011; Zeisberg and Neilson, 2009).