5.4. Cell Viability Assay

U87MG cells were seeded in 96-well plates (5 × 10³ cells/well) and treated with Iso at three different concentrations (10, 15 and 25 µM) by only one induction; DMSO 0.1% was added in the control. At 24, 48, and 72 h of treatment, cell viability was evaluated by MTT assay. Briefly, 10 µL of 5 mg/mL MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; Sigma-Aldrich) was added in each well with 100 µL of medium. After 1 h of incubation at 37 °C, formazan crystals were dissolved with 100 µL isopropanol/HCl 0.4% and the absorbance was measured at 570 nm with a plate reading spectrophotometer.