2.9. MTT assays to assess cell proliferation

Cell proliferation was estimated using an MTT assay (Sigma-Aldrich). Briefly, cells were seeded in 96-well plates. After transfection with 1 pmol of miRNA mimics, miRNA inhibitors, or the negative control, cells were incubated for 1, 2, or 3 days without changing the medium after transfection. At each time point, 50 μL of MTT (2 mg/mL) were added to the wells, and the cells were cultured at 37°C for 4 hours. After removing the media, 150 μL of dimethyl sulfoxide (DMSO) were added and the solution was mixed for 10 minutes. The optical density was determined at 570 nm using a microplate reader (BioTek Instruments, Inc., Winooski, VT).