RHOA and oral cavity squamous cell carcinoma: Previously, it has been found that PDPN is associated with the down-regulation of the cell-cell adhesion protein E-cadherin in oral squamous cell carcinomas [2] and that it induces an epithelial-mesenchymal transition in Madin-Darby canine kidney type-II epithelial cells and immortalized HaCaT keratinocytes through the interaction with ERM proteins and up-regulation of RhoA activity [6].