FIG. 4.

The V protein of SV5 induces proteasome-mediated degradation of STAT1. (a) 2fTGH cells were mock infected (lane 1) or infected with recSFV/F (lane 2), recSFV/lacZ (lane 3), or recSFV/V (lane 4) for 8 h, and total-cell extracts were probed for STAT1 as previously described. (Immunofluorescence analysis confirmed that >95% of the cells were expressing the appropriate virus proteins at the time of harvest.) (b) 2fTGH cells were mock infected (lanes 1 and 2) or infected with recSFV/V (lanes 3 and 4). The proteasome inhibitor MG132 (10 μM) was (lanes 2 and 4) or was not (lanes 1 and 3) added to the culture medium at the time of infection. At 8 h p.i., cells were harvested and levels of STAT1 were estimated by immunoblot analysis.