FIG. 1.

Ectopic Brd4 expression inhibits cell growth. (A) Reduced colony formation by NIH 3T3 cells expressing ectopic Brd4. Cells (10⁵) were transfected with an empty vector, pcxn (Control) or pcxn2-Brd4 and selected in G418 for 2 weeks (upper panels). Colonies were stained with methylene blue. The graph shows the number of colonies per plate in cells transfected with the control or Brd4. Also shown are the results of immunoblot analysis of Brd4 protein expression in control (pcxn2) or pcxn2-Brd4 transfectants (lower right panels). YY1 was used as a control for protein loading throughout this work. (B) TET-inducible Brd4 expression. TET-inducible cells were treated with DOX at the indicated doses for the indicated hours, and Brd4 expression was detected by immunoblot analysis. (C) TET-induced inhibition of cell growth. Parental or TET-inducible cells were treated with DOX (2 μg/ml) or left untreated, and cell numbers were counted on the indicated days (left panels). Inducible Brd4 expression was monitored by immunoblot analysis (right panels).