SOX2 and glioblastoma: On the other hand, BLAST analysis of SOX2 exon region from 543 to 731 for exosomal PCR products revealed that NSC derived exosomes had 3 single nucleotide insertions at 181712483, 181712512 and 181712573 each; GBM derived PCR product had a deletion at 181712512: (C > -), and CD133+ GBM derived exosomal product had 100% identity to SOX2 (supplementary material S4 Fig).