SOX9 and cancer: SOX9 is a high‐mobility group box (HMG‐box) factor that is a key regulator of stem cell population maintenance.[19, 20] Recent studies have shown that SOX9 expression is crucial for stemness maintenance in various types of cancers and that SOX9 knockdown significantly blocks cancer stem cell phenotype development.[21, 22, 23] SOX9 is highly expressed in GBM and is considered an essential factor driving GBM stem cell phenotype and self‐renewal, which significantly remodels sensitivity to chemotherapy.[24, 25, 26]