Fig 7.

DHX33 protein induction plays a crucial role in Ras^V12-enhanced rRNA transcription. (A) Arf-null ear fibroblasts from 2-month-old mice were infected with either empty vector or Ras^V12-encoding retroviruses. Total RNA was extracted and analyzed by RT-PCR for 47S pre-rRNA levels. Error bars indicate standard deviation from three independent experiments. (B, C, and D) Arf-null ear fibroblasts were infected with retroviruses encoding empty vector or Ras^V12. At 2 days postinfection, the cells were then infected with lentiviruses encoding shScrambled (SCR) or shRNA-DHX33 for 3 days. Cells were then subjected to Western blot analysis for DHX33 protein levels (B). Equal numbers of cells were pulsed with [³H]uridine and chased at the indicated time points, the total RNA was isolated and separated for rRNA synthesis analysis, and a representative result from three independent experiments is shown (C). The cells were then pulse-labeled with [³⁵S]methionine incorporation and ³⁵S-labeled proteins were measured. Error bars represent the standard deviation from three independent experiments (D). **, P < 0.001.