SNAI1 and head and neck cancer: Through decreasing the level of E-cadherin expression, overexpression of Snail or Twist has been reported to be an essential agent for induction of tumor progression, further aberrant regulation of Snail or Twist has also been demonstrated in different types of epithelial tumors, such as gastric (Rosivatz et al., 2002), prostate (Yuen et al., 2007), breast (Martin et al., 2005), head and neck cancer (Yang et al., 2008).