CD44 and cancer: Expression of different CD44 isoforms positively correlates with poor clinical outcome in various cancers, such as breast (24–26), colon (27), lung (28), bone (29), pancreatic (30), colorectal (31), bladder (32), gastric (33), and head and neck squamous cell carcinomas (34), as well as leukemias (35) and lymphomas (36).