FIG. 4.

The suppression of Dicer and RISC extracts at late times of adenovirus infection is specific. (A) An adenovirus infection does not inhibit protein kinase activity against a recombinant ASF/SF2 protein. Cytoplasmic extracts prepared from uninfected 293 cells (U) or cells infected with wild-type adenovirus for 8, 16, or 24 h were tested for their capacity to phosphorylate ASF/SF2 in vitro. Products were resolved on a 12% reducing SDS-polyacrylamide gel and subjected to autoradiography. (B) Restoration of Dicer activity in infected extracts by increasing the concentration of the dsRNA substrate. Dicer activity in cytoplasmic extracts prepared from uninfected or adenovirus-infected (16 h postinfection [hpi]) 293 cells was assayed against a ³²P-labeled GL2 dsRNA. The figure shows the Dicer activity in infected extracts relative to uninfected extract at concentrations of 5, 20, and 100 nM dsRNA. The mean values and standard deviations from three independent experiments are shown. For further details see Fig. S1 in the supplemental material.