Fig. 3. PP2A inhibitors depress pol III transcription in extracts of mitotic HeLa cells. (A) Mitotic repression of pol III transcription can be accentuated using okadaic acid or calyculin A. pGlu6 (500 ng) was transcribed using 25 µg of mitotic extract that had been pre-incubated for 10 min at 30°C in the presence of buffer alone (lane 1), 100 or 0.2 nM okadaic acid (lanes 2 and 3, respectively), and 100 or 0.2 nM calyculin A (lanes 4 and 5, respectively). (B) PP2A inhibitor polypeptide depresses pol III transcription in extracts of mitotic HeLa cells. pVAI (250 ng) was transcribed with 25 µg of mitotic extract pre- incubated for 10 min at 30°C in the presence of buffer alone (lanes 1 and 4), and 25 or 100 ng of I₁^PP2A (lanes 2 and 3, respectively).