SOX2 and central nervous system cancer: Self-renewal capacity of a CSC is critical and enables the maintenance of the CSC subpopulation within a tumor and SOX2 has shown to mediate this in breast, gastric, ovarian, prostate cancer, glioma, osteosarcoma, lung adenocarcinoma and NSCLC [15,42,54,59,65,66,77,82,83].