FIG. 4.

2′5′ A synthetase activity in IFN-treated cells and cells overexpressing PML. 2′5′ A synthetase activity was determined in cells extracts from CHO control cells (lane 1). CHO PML3 (lane 2), GP+E−86 control cells (lane 3), GP+E−86 PML (lane 4), U373 MG control cells (lane 5), U373 MG PML (lane 6), and U373 MG cells treated for 48 h with 10 U of IFN-β per ml (lane 7). All control cells are cells transfected with the empty vector. The 2′5′ A synthetase activity was determined by chromatographic analysis of the reaction substrate (ATP) and the products, 2′,5′-oligoadenylates (dimer and trimer), as previously described (7).