MTT cell proliferation assay

A549 and H1299 cells were cultured in 96-well microplates (3,000 cells/well). After transfection, the cells were cultured for 24, 48, 72, and 96 hours, and then, 20 µL of MTT solution (5 mg/mL; Solarbio, China) was added into each well. The cells were subsequently treated with 200 µL dimethyl sulfoxide (DMSO; Solarbio, China) after incubation for 4 hours in absolute darkness. Finally, the absorbance of the cells was detected at 490 nm using a microplate reader. These experiments were repeated 3 times.