FIG. 4.

EBNA-LP is associated with active PKA. Immune precipitates from BJAB (B), BFLP, BFLPd10, or BFLPW4 cells were immune precipitated with M2 beads. The immune precipitates were split and assayed for PKA based on phosphorylation of a specific substrate (Kemptide; Upstate Biotechnology) using [γ-³²P]ATP in the presence (dashed lines) or absence (solid lines) of PKA inhibitor (PKA INH). The labeled Kemptide was blotted on P81 phosphocellulose paper (boxed figure). Radioactivity was measured with a PhosphorImager (Molecular Dynamics), and relative counts are indicated in the graph as kinase activity.