IGFBP2 and glioma: Notably, the function of IGFBP2 in glioma cell malignancy and VM was found to be partially countervailed when overexpressing HOTAIRM1 in IGFBP2 silenced U251 cells or silencing HOTAIRM1 in IGFBP2 overexpressing U251 cells (Fig. 5B–E).