**2.7. Annexin V-FITC assay**

Apoptosis was also investigated by detection of externalized phosphatidylserine using the Annexin V Kit (BD Pharmingen, USA). The cell preparation was carried out in accordance with the manufacturer's protocol. The prepared cells were finally subjected to flow cytometric analysis using laser emitting excitation light at 488 nm and a BD flow cytometer equipped with an Argon laser (Cyan ADP, DAKO, Glostrup, Denmark). The data were analyzed using the Summit V4.3 software.
