FIG. 5.

Phosphorylation of rpS6 is not sufficient to enable efficient translation of TOP mRNAs. (a) Cytoplasmic extracts were prepared from four proliferating lymphoblastoid cell lines (WHI1660, WHI1249, WHI1615, and WHI1860) or from P1798 cells which were either dividing (Con or C) or nondividing due to 24 h of dexamethasone treatment (Dex or D). The polysomal distribution of the mRNAs encoding rpL32 and actin was analyzed and presented as described in the legend to Fig. 1. (b and c) Cytoplasmic proteins from the cells mentioned in panel a were subjected to Western blot analysis with the indicated antibodies.