HOTAIR and glioblastoma: Indeed, the expression of HOXA9 in GBM is known to be epigenetically regulated by the PI3K pathway via inhibition of EZH2-mediated H3K27 trimethylation at the HOXA9 locus [36], and HOTAIR is known to interact with PRC2 complex (containing EZH2 and other subunits) to guide it to target loci [10, 13, 37].