PAX6 and glioblastoma: A 57 bp cis‐regulatory element named E1E (exon 1 enhancer) in the first exon of PAX6 plays an important role in the expression of this gene in glioblastoma cell lines (23), and a powerful silencer (SX250) located between 1518 and 1268 bp from the A of the ATG codon is able to repress the promoter activity of PAX6 in cervical carcinoma and glioblastoma cell lines (22).