SNAI1 and cancer: In cancer progression, epithelial–mesenchymal transition (EMT) begins with the loss of epithelial cell polarity, transformation into mesenchymal cells, followed by upregulation of N-cadherin, Vimentin, Snail, Slug, Smad 2/3, Twist, and Zeb1/2 as well as matrix metalloproteinase (MMP) expression, whereas inhibits the expression of the epithelial marker, E-cadherin [24,25].