Fig. 4

PG induces cell cycle arrest at the G1 phase. SAECs were cultured with 4% PG or Gly for 24 h. A Distribution of cell cycle phase in each group by flow cytometry. Data were compared with the control sample in the same phase respectively. B Relationship of p21 and cell cycle. C Effect of PG and Gly on p21 expression. Representative western blot images are shown. β-actin was used as a loading control. Band size is indicated on the upper right. Densitometric analysis of p21 expression, normalized to that of β-actin. Data are expressed as a relative value to control (without PG and Gly, indicated as a grey bar). Three batches of SAECs were evaluated on two separate occasions. Values are mean ± SEM. Statistical significance was determined using two-way ANOVA. PG propylene glycol, Gly glycerol, SAECs small airway epithelial cells, SEM standard error of the mean