*2.2. Transfection*

In order to explore the functional roles of miR-21 in GBM cells, the upregulation or downregulation of miR-21 was achieved using mimic and inhibitor, respectively. MiR-21-5p mimic (HMI0372, Sigma, St. Louis, MO, USA) and inhibitor (HSTUD0371, Sigma, St. Louis, MO, USA) were transfected into GBM cells using Lipofectamine 2000 reagent (Invitrogen, USA) according to the vendor's instructions. The change in the expression of miR-21-5p was then determined by real-time PCR (RT-PCR) 48 h post-transfection in both GBM cell lines. hsa-miR-21-5p primers (MPH02337, Abm, Richmond, BC, Canada) were purchased and used for qPCR experiments.
