Cell Counting Kit-8 (CCK-8) assay

A549 cells were maintained in the exponential phase and then seeded in 96-well plates (2×10⁴ cells/well). Cell proliferation was detected using a CCK-8 assay (Shanghai YiSheng Biotechnology Co., Ltd.) according to the manufacturer's instructions. At the indicated times of 24, 48 and 72 h, 10 µl CCK-8 solution was added to each well and the cells were incubated for an additional 4 h at 37°C. The optical density was measured at 450 nm using a microplate reader (Bio-Rad Laboratories, Inc.).