HOTAIRM1 and glioblastoma: To determine effects of genetic knock-down of HOTAIRM1 in glioma cells, we first performed a transient siRNA-mediated knock-down of HOTAIRM1 in the four established glioblastoma cell lines U251MG, LN-229, LN-18, and T98G (Fig. 2A–D), which showed an intermediate expression level (Supplementary Fig. 2).