CDH2 and pemphigus foliaceus: EMT is a multifunctional process in which epithelial cells lose the epithelial phenotype and acquire the mesenchymal phenotype, accompanied by down-regulation of epithelial cell marker (e.g., E-cadherin) and upregulation of mesenchymal cell marker (e.g., N-cadherin and Vimentin), thereby promoting PF development (Thiery et al., 2009; Peng et al., 2020).