CD44 is a receptor for hyaluronic acid and can also interact with other ligands, such as osteopontin, collagens and matri, Xenopus/Amphibian, metalloproteinases (MMPs). CD44 function is controlled by its posttranslational modifications. One critical modification involves discrete sialofucosylations rendering the selectin-binding glycoform of CD44 called HCELL (for Hematopoietic Cell E-selectin/L-selectin Ligand). The HCELL glycoform was originally discovered on human hematopoietic stem cells and leukemic blasts, and was subsequently identified on cancer cells.