Cisplatin treatment and cell viability assay

Each cell line (1 × 10⁴ cells in 100 μl of medium) was seeded in a well of a 96-well plate, and each seeding was performed in triplicate. The medium was changed the following day to medium containing with various concentrations of cisplatin (0–50 μM) for 48 h. Cell viability was then assessed using a Cell Counting Kit-8 (Dojindo Molecular Technologies, Inc.) according to the manufacturer’s protocol. The absorbance at 450 nm was measured using a multilabel counter ARVO MX (Perkin Elmer, Inc., MA, USA). The inhibitory concentration (IC)₅₀ was calculated from the rate of cell survival after normalization by the probit transformation.