ZEB1 and glioblastoma: Gene silencing of SNAIL reduces GBM cell invasion, migration and proliferation, while ZEB1 and ZEB2 promote the upregulation of proteins related to the mesenchymal phenotype, such as N-cadherin, vimentin and fibronectin, and the downregulation of proteins related to the epithelial phenotype e.g., E-cadherin, claudins, occludins and cytokeratin [16].