MTS Viability Assay for Glioblastoma Stem Cells

MTS viability assays were described previously [41 (link), 58 (link)]. In brief, 2.5 × 10³ GSCs were plated in a 96-well plate. Cells were then treated with DMSO, 50 μM of TMZ, 100 μM of αCT1, or a combination of TMZ and αCT1. αCT1 treatment was repeated every fourth day for 2 doses. In another set of experiments, cells were treated with imatinib or γ-secretase inhibitor IX as described above. After one week, cell viability was monitored using the MTS assay. 10 μl of MTS (Promega) was added to each well, then incubated at 37°C for 1 h. The absorbance at 490 nm was measured using a FilterMax F3 microplate reader (Molecular Devices, LLC) according to manufacturer's instructions. Percent cell viability was obtained by dividing the absorbance of treatment groups with those of untreated groups.