MTT assay

Cell viability was measured by MTT assay. Approximately 200 µl cells at the concentration of 1×10⁴/ml were seeded into 96-well plates. After incubation of cells for 24 h, 20 µl of 5 mg/ml MTT solution was added to each well and the plate was further incubated at 37°C for another 4 h. Afterwards, wells were rinsed with PBS for 3 times, and 150 µl DMSO was added into each well. The microtitre plate was placed on a shaker to dissolve the dye thoroughly. Absorbance at 450 nm was read using a Bio-Rad iMark plate reader.