“…These lesions are associated with aberrant cell proliferation and differentiation, which eventually leads to loss of tissue homeostasis. A tremendous number of clinical studies have focused on the epidemiology and pathogenesis of intestinal metaplasia and dysplasia in humans ( Correa and Houghton, 2007 ; Harpaz and Polydorides, 2010 ; Kapoor et al, 2015 ), and studies in animal models, including in mice and flies, have greatly expanded our knowledge of the mechanisms that cause these lesions at the cellular and molecular level ( Li et al, 2013a ; Liu et al, 2013 ; Mari et al, 2014 ; Quante et al, 2012a ). In the closing sections of this Review, we discuss these studies particularly in the context of our emerging understanding of how intrinsic and extrinsic factors cause GI epithelial dysfunction, and how dysregulation of GI stem cells is related to these lesions.…”