EPAS1 and glioblastoma: Moreover, the down-regulation of histone methyltransferase mixed-lineage leukaemia 1 (MLL1) by shRNA in GBM cells, which is induced under hypoxic condition, was also effective at reducing the expression of HIF-2α protein and its target genes, including VEGF and inhibiting the self-renewal, growth and tumourigenicity of GSCs [108].