Objective: Pancreatic ductal adenocarcinoma (PDA), the fourth leading cause of cancer death in the United States, is a nearly uniformly fatal disease.Recently, an increasing number of studies have suggested that a high level expression of CD44,early signs of epithelial-mesenchymal transition (EMT), and early metastatic presentation all contribute to poor outcomes and treatment response in PDA patients.Most of the studies that have related CD44 to PDA focused on CD44 as a cancer stemlike cell marker.However, the roles of CD44 in PDA invasion and metastasis have not been fully elucidated.