ZEB1 and neoplasm: Because TGF-β treatment upregulates EMT-inducing transcription factors, such as SNAI1 and ZEB1, via activation of MEK-ERK signaling, it upregulates the expression of mesenchymal markers, such as N-cadherin, vimentin, and α-SMA, and downregulates the expression of epithelial markers, such as E-cadherin, claudins, and ZO-1, which are involved in tumor invasion, metastasis, and cell motility [4,35].