Cytotoxicity assay for human gastric cancer cells by 5-fluorouracil

To determine the 50 % inhibitory concentration (IC₅₀) of 5-FU for NCI-N87 and MKN-45 cells, we performed 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) assay. The cells were seeded at 1 × 10⁴ cells per well in a 96-well microplate, and exposed to various concentrations of 5-FU (0, 0.03, 0.1, 0.3, 1, 3, 10, 30, 100, 300 and 1000 μΜ) for 48 h at 37 °C in 5 % CO₂. After the treatments, CellTiter 96® Aqueous One Solution (Promega, Madison, WI) was added to each well, followed by incubation for 2 h at 37 °C in 5 % CO₂, and the absorbance of each well was measured using a microplate reader (iMark, Bio-Rad, Hercules, CA) at 540 nm.