MTT assay

Following digestion by trypsin, MDA-MB-231 cells in logarithmic growth phase were resuspended in complete medium (RPMI-1640 medium supplemented with 10% FBS and 1% penicillin and streptomycin). Cells were plated at a density of 5×10³ cells/well into 96-well plates. Following incubation at 37°C for 48 h, 20 µl MTT reagent (5 mg/ml) was added to each well and incubated at 37°C for 4 h. Finally, 100 µl dimethyl sulfoxide was added to completely dissolve the purple formazan crystals. The absorbance of each well was measured at 492 nm using a multi-functional microplate reader for evaluation of cell viability.