5. Flow cytometry analysis of cell apoptosis

Apoptotic cells were identified using the Propidium Iodide (PI) and FITC Annexin V Apoptosis Detection Kit I (BD Biosciences, San Jose, CA, USA) according to the manufacturer's instructions. After 24 hours of transfection, SiHa or Caski cells were cultured for 72 hours before determining apoptosis. The cells were harvested, washed twice with cold phosphate-buffered saline (PBS), and resuspended in 1× binding buffer. Then, the cells were stained with 5 µL Annexin V-FITC for 15 minutes and then 5 µL PI for 10 minutes in the dark at room temperature. The cells were examined using a FACSCanto II flow cytometer (BD Biosciences Europe, Heidelberg, Germany).