HOTAIRM1 and glioblastoma: Lentivirus stably expressing short hairpin RNAs targeting HOTAIRM1 (shRNA-1, shRNA-2 and shRNA-3), as well as the scramble sequence (sh-ctrl), were introduced into GBM cells, and qRT-PCR analysis confirmed the knockdown of HOTAIRM1 in U251 and pGBM1 cells (Figure 2A).