The development and metastasis of tumor is a multi-step process and involves a lot of genetic alterations.Cell adhesion molecule,E-cadherin is capable of maintaining the polarity of epithelial cells and cell junction.Reduced expression of E-cadherin has been regarded as one of the main molecular events involved in dysfunction of the cell-cell adhesion system,triggering cancer invasion and metastasis.Loss of E-cadherin expression or function was observed in many gastric cancer cells.A direct role for E-cadherin in the suppression of tumor invasion has been demonstrated by the reversion of undifferentiated,invasive tumors to a differentiated phenotype after the transfection of E-cadherin cDNA in cell culture models.