MTT assay

To examine changes in cell viability, cells were seeded at a density of 6 × 10³ cells/well in a 96-well culture plate. After 24 hours, the cells were transfected with the appropriate plasmid. Twenty-four hours post-transfection, the medium was replaced with medium containing different concentrations of cisplatin. Twenty-four hours post-cisplatin treatment, MTT reagent was added (Calbiochem) and the cells were incubated for 3.5 hrs at 37° C. After incubation, the media was aspirated off, crystals were dissolved in MTT solvent (4 mM HCl, 0.1% Nonidet P-40, in isopropanol), and viability was assessed by measuring the absorbance at 570 nm with 630 nm absorbance as the reference. Percent viability is expressed as the absorbance normalized to the DMSO control.