TABLE 2.

Biological functions of different CD44 isoforms in cancer.

CD44 isoforms	Biological functions	References
CD44s	Tumorigenesis, tumor growth, aggressive behavior, micrometastasis events, inhabiting stemness, CSCs characteristics, EMT	13 , 52 , 61 , 62 , 93 , 107 , 138 , 180
CD44v	Invasiveness, stemness, tumor growth	62 , 64 , 120
CD44v3	Metastasis, EMT	221
CD44v4, v5, and v7	Growth and proliferative activity	108
CD44v6	EMT, aggressive behavior, poor prognosis,	34 , 54 , 139 , 223
CD44v8–v10	Tumorigenic phenotypes, aggressive behavior, poor prognosis, restoration of tumor‐initiating potential, tumor growth	52 , 76 , 83 , 94 , 103 , 119 , 120
CD44v9	Progression and metastasis, poor prognosis, EMT	14 , 93 , 101
CD44v10	Cell proliferation	199