Cell cycle assay
AnnexinV- FITC/PI probe was used to evaluate the cell cycle. Briefly, the cells were treated with PA and/or different concentrations of samples. After 24 h incubation, the cell medium was discarded, and the cells were washed thrice with pre-cooled PBS. The cell pellet was suspended in a binding buffer, and then continuously stained with PI and Annexin V-FITC for 15 min in the dark. The samples were analyzed within 1 h after staining. The cells were measured by a Cyto FLEX flow cytometer (Beckman Coulter Company, USA).