SNAI1 and infection: Additionally, infection-mediated induction of the epithelial-to-mesenchymal transition (EMT) in host epithelial cells has been consistently reported over the past decade, including upregulation of mesenchymal markers such as N-cadherin, MMP9, and fibronectin, as well as the pro-EMT regulators ZEB1/2, SNAIL/SLUG, and thrombospondin 1 (16, –, 18).