CD44 is an adhesion molecule, which binds hyaluronic acid and participates in a number of cell-cell interactions, including lymphocyte homing.CD44 is expressed on approximately 90% of lymphocytes, monocytes, granulocytes, and, in lower amounts on thymocytes, fibroblasts, and erythrocytes. The expression of specific cell adhesion molecule CD44 splice variants has been reported to be associated with metastasis in certain human malignancies.