SOX2 and glioblastoma: Positive CTCs were then characterised by using a ‘cocktail’ of antibodies against SOX2, tubulin β-3, EGFR, A2B5 and c-MET based on GBM biomarkers identified in the literature, before the expression of 25 genes, representing all the molecular subtypes of GBM (proneural, neural, classical and mesenchymal), was assessed; the results of the analysis concluded that CTCs from GBM show more of a mesenchymal phenotype.68 This phenotype is associated with a higher invasion capacity, allowing cells to intravasate into the circulation, which may explain the rare cases of extracranial metastases in GBM.