Cell Counting Kit (CCK)-8 Assay

Cell viability was examined using a Cell Counting Kit-8 (Dojindo, Kumamoto, Japan) as previously described (25). The GBM cells were seeded into 96-well plates with 3,000 cells per well and cultured overnight, followed by the addition of different concentrations of OTSSP167. After 72 h of treatment, 10 μL of CCK-8 solution were added to each well, followed by incubation for 2 h and measuring the absorbance (optical density, OD) at a wavelength of 450 nm. Three independent experiments were conducted with each experiment having three replicate wells, and the background reading of media was subtracted from each well for result standardization.