CD44 and central nervous system cancer: Further studies revealed that Sox2 was a crucial player in maintaining the stemness of GSC (Glioma stem cells) through miR-9 [44], CSCs in HNSCC (Head and Neck squamous cell carcinoma) through miR-302 [45], CSCs in breast tumors [25], mammalian neural stem cells [46], CD44+ cancer stem-like cells in EBV-associated nasopharyngeal carcinoma [47], cancer stem-cell from squamous-cell carcinoma [48] and SP (side population) cells in NSCLC [15].