Induction of neuronal differentiation of tumor-derived neural stem cells by miR-124 and miR-137. (A) Epifluorescent images of tumor-derived neural stem cells 72 hours after transfection with miR-124, miR-137, control oligonucleotides and lipofectamine reagent alone. Cells were immunostained with Tuj1 and glial fibrillary acidic protein antibodies and DNA was stained with Hoechst 33258 reagent. The percentage of Tuj1- and glial fibrillary acidic protein-positive cells was quantified in each sample after transfection and staining and plotted against the total number of counted cells (n = 450). (C) Quantification of Tuj1+ and glial fibrillary acidic protein+ cells in primary glioblastoma multiforme cultures 10 days after transfection of miR-124, miR-137 or control oligonucleotides. The inset shows a Tuj1+ cell with neuronal morphology from a miR-124 and/or miR-137 cotransfection. (D) Immunostaining with neuronal markers Tuj1 and microtubule-associated protein 2 10 days after miR-137 or negative control miR-transfections in glioblastoma multiforme lines maintained as neurospheres.