SOX2 and esophageal squamous cell carcinoma: TWIST-related protein 1 (TWIST1), a transcription factor (TF) of epithelial-mesenchymal transition (EMT), induces the CSC phenotype and amplifies it by coordinating EMT; enhances N-cadherin, occludin, vimentin and ZEB2 expression; promotes the expression of BMI1; induces proliferation and invasion of ESCC cells; and promotes long-term proliferation and differentiation inhibition of ESCC stem cells by increasing the expression levels of stemness TFs KLF4 and SOX2 in KYSE-30 cells [13].