Tumor hypoxia is a common feature of the microenvironment in solid tumors, which regulates the transcriptional factors such as ZEB1/2, TWIST, zinc finger protein SNAI1 (SNAIL), E2A proteins, and E2A immunoglobulin enhancer-binding factors E12/E47 (E12/E47) to downregulate the epithelial cell markers E-cad expression and induce mesenchymal gene expression. This evidence concerns the gene SNAI1 and neoplasm.