Cell viability assay

Transfected SAS and SCC-4 cells were seeded into 96-well plates (3000 cells/well). After overnight incubation, 200 μl of culture medium was dispensed into each well. Following 72-h treatment, 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) dye (Calbiochem, CA, USA) was added. After 2 h of incubation, the medium and MTT dye were removed by slow aspiration and 100 μl of dimethyl sulfoxide (DMSO) was added to dissolve the remaining MTT formazan crystals. The absorbance at 550 nm was measured using a 96-well plate SpectraMax 250 reader (Molecular Devices, CA, USA).