Fig. 4.

The roles of p53 on regulating TGEV N protein-induced cell cycle arrest and apoptosis. (A) Effect of PFT-α on the changes of cell cycle progression induced by TGEV N protein. PK-15 cells were transfected with N-EGFP expression vector or EGFP empty vector and treated with PFT-α for 36 h. Cells were collected and stained with propidium iodide for FACS analysis. (B) Effect of PFT-α on the apoptosis induced by TGEV N protein. PK-15 cells were transfected with N-EGFP expression vector or EGFP empty vector and treated with PFT-α for 48 h. Cells were collected and stained with annexin V and PI for FACS analysis. Values are mean ± SD. ^∗P < 0.05 versus TGEV N gene expressed cells without PFT-α. (C) Effects of PFT-α on the expression of cell cycle and apoptosis regulating factors. PK-15 cells were transfected with N-EGFP expression vector or EGFP empty vector and treated with PFT-α for 24 h. Cells were collected and subjected to Western blot analysis. Cox4 and actin were used as internal controls for the mitochondrial fractions and the cytosolic fractions, respectively. (D) Effects of PFT-α on caspase-3 activity. PK-15 cells were transfected with N-EGFP expression vector or EGFP empty vector and treated with PFT-α for 48 h. Cells were collected and the activity of caspase-3 was measured by colorimetric assay kit. Results are means ± SD. ^∗P < 0.05 versus TGEV N gene expressed cells without PFT-α.