Figure 2. Response of cotylenin A on cell death and apoptosis in retinoblastoma cell lines. A: Detection of apoptosis using a terminal deoxynucleotidyl transferase deoxyuridine 5′-triphosphate (dUTP) nick-end labeling (TUNEL) assay. Cells were treated with or without 10 μg/ml cotylenin A (CN-A) for 7 days. The bar represents 25 μm. The arrow points to TUNEL-positive cells. B: The bar graph indicates the percentage of TUNEL-positive cells. Asterisks indicate significant differences when compared with the control without CN-A (p<0.05; C) the bar graph and electrophoresis photographs indicate the protein expression of cleaved- Poly Adenosine diphosphate –ribose polymerase (PARP) in retinoblastoma cells. The bar graph indicates C-PARP protein expression (n=3); the error bar indicates the standard deviation. Asterisks indicate significant differences when compared with the control without CN-A (p<0.05).