Flow cytometry assay

Equal numbers of cells transfected with lentiviral vector were cultivated in each well of a 6-well plate. All cells were collected using trypsin solution (without EDTA, Nalgene, Rochester, NY, USA) and stained with a fluorescein isothiocyanate Annexin V Apoptosis Detection kit (BD Pharmingen, Franklin Lakes, NJ, USA). A flow cytometer (BD Biosci-ences, San Jose, CA, USA) was employed to determine the apoptosis ratio of the cells. Glycerol was supplemented at the concentrations indicated above. Rapamycin was added at concentration of 1 µmol/L.28