SOX2 and nasopharyngeal carcinoma: To establish whether these morphological changes were due to an early differentiation of NPC in the presence of FGF2, we studied their phenotype by immunocytochemically detecting the expression of Nestin (component of intermediate filaments characteristic of NPC [26], [27]), Sox2 (transcriptional factor restricted to neural stem cells with multipotent and self-renewal properties [28]), β-III Tubulin (early neuronal marker, identified by TUJ1 antibody) and GFAP (astrocyte marker).