Figure 4.

Characterization of inducible cyclin A expressing cells. (A) Cyclin A expression analysis. Brl-pMT Cyc A-1 and Br1-pMT Cyc A-2 cells were treated with 300 μM PALA for 48 h with simultaneous induction of cyclin A with 100 μM Zn²⁺ for 9 h. (B) Percentage of Br1-pMT CycA-l (open squares) and Br1-pMT CycA-2 (solid squares) cells undergoing apoptosis in controls, Zn²⁺ alone, PALA alone and PALA + Zn²⁺ at different time intervals. (C) DNA fragmentation in Br-l pMTCyc A-I and Brl-pMTCyc A-2 cells: Lane 1, Control; 2, Zn²⁺ treated; 3, PALA treated; 4–9, PALA + Zn²⁺ treated and harvested at 0 h, lanes 4 and 7; 4 h, lanes 5 and 8; and 24 h, lanes 6 and 9. (D) E2F1 DNA binding assay in BR 1-pMTCyc A-1 cells: Nuclear extracts from control, 300 μM PALA and 300 μM PALA + Zn²⁺ treated cells.