Figure 4.

ADI-PEG20 induces caspase-dependent apoptosis in ASS1-methylated lymphoma cell lines. (a) The three cell lines were treated with ADI-PEG20 (0–500 ng/ml) for 4 days. Cells were then harvested and fixed in 70% ethanol for at least 24 h. The apoptotic fraction of cells, identified as the sub-G1 population of cell cycle was measured by flow cytometry with propidium iodide staining (described in Materials and Methods); *P<0.05 represents statistical significance compared with untreated cells for each cell line; protein lysates from (b) NcNc (c) Karpas-422 and (d) MyLa cells treated with ADI-PEG20 (0–500 ng/ml) were analysed by western blotting for the expression of ASS1 and the detection of cleaved PARP and caspase-3