2.3. Cell viability assay

In this study, MTT assay was used to detect the growth ability of the cells. The cells at a density of 1000 cells/well were inoculated in 96-well plate at the final volume of 200 μl, and then reagents or inducers were added after 24 h. After that, cells were cultured in a medium containing MTT (5 mg/ml in PBS) (Sigma-Aldrich, St Louis, MO, USA) for 4 h, and the dimethylsulfoxide (DMSO) (150 μl) was added to dissolve the crystals in each well, and then continued to incubate at 37.0 °C for 10 min. The absorbance (OD) was tested at 540 nm wavelength. The reagent (3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium bromide (MTT)) used in this experiment was acquired from Sigma (Sigma-Aldrich, St Louis, MO, USA).