HOXA9 and glioblastoma: Interestingly, WNT6 expression was significantly increased upon HOXA9 overexpression in U87 cells (Fig. 3C) and decreased upon HOXA9 silencing in U251 cells (Fig. 3D), strongly suggesting that HOXA9 binding to the WNT6 promoter region promotes WNT6 expression in GBM.