Figure 4.

Activation of endogenous PKR by dsRNA. (A) U4C and P2.1 cells were untreated or treated with 100 μg/ml of dsRNA for the times shown above each lane. The cells were washed with PBS to remove bound dsRNA and were lysed in assay buffer. PKR was immunoprecipitated from 100 μg of total cell lysate and was incubated with 10 μCi of γ-³²P-labeled ATP for 10 min at 30°C. (B) Western analysis of PKR protein by using a mAb. The sizes of molecular weight standards are indicated in kilodaltons.