Protein synthesis in exPKO acinar cells. (A) Before the onset of massive cell death, protein synthesis is normal in the mutant pancreas. The graph shows the average of two independent experiments ([35S]Met/Cys incorporation) with a total of 4 replicates, using lobules isolated from P17 exPKO and wild-type littermates. TCA-precipitable radioactivity was normalized to the protein concentration of total lysate. (B) Protein synthesis in older exPKO mice is significantly reduced. Lobules were isolated from P63 exPKO (lanes 2, 4, 6) and wild-type (lanes 1, 3, 5) littermates and incubated for 0, 30, and 60 minutes with [35S]Met/Cys and 10 mg of total protein per lane were separated electrophoretically. The arrow indicates the position of amylase, which is the predominant zymogen in the exocrine pancreas and is readily detectable in whole radiolabeled protein. This gel was exposed for a short period and other proteins in this molecular weight range were not visible.