CD44 and neoplasm: TM4SF5 has been shown to form protein–protein complexes with CD44 (114), CD133 (115), CD151 (116), epidermal growth factor receptor (EGFR) (117), insulin-like growth factor 1 receptor (IGF1R) (118) and integrin-α5 (119) on the cell surface and play roles in tumor cell migration and anticancer drug resistance.