SNAI1 and neoplasm: During cancer progression, tumor cells with epithelial features generally acquire mesenchymal traits through increased expression of EMT-related transcription factors (EMT-TFs), such as the twist family bHLH transcription factor (TWIST), snail family transcriptional repressor 1 (SNAIL), snail family transcriptional repressor 2 (SLUG) and zinc finger E-box binding homeobox 1 (ZEB), the expression levels of which vary according to tumor type.