The research of Costa et al. also showed that the PI3K/AKT/mTOR signaling pathway is a critical regulatory mechanism of HOXA9 gene expression in GBM, and PI3K inhibitor LY294002 treated in A172 cells leads to a reduction of HOXA9 expression, which is associated with reversible epigenetic histone modifications [30]. The gene discussed is HOXA9; the disease is glioblastoma.