Cell death enzyme-linked immunosorbent assay (ELISA)

Apoptosis was also verified by using Cell Death Detection ELISA^PLUS Photometric Enzyme Immunoassay Kit (Roche Diagnostics GmbH, Mannheim, Germany). In brief, 1 × 10⁴ cells were harvested and lyzed in 200 μl of lysis buffer provided by the kit for 30 min at room temperature followed by centrifugation at 200 × g for 10 min. 20 μl of supernatant was then added to ELISA microplate for quantification of cytoplasmic histone-associated DNA fragments according to the manufacturer's instructions.