mean6SD of four replicates. Similar transfection efficiencies were obtained with the three vectors and cell counts were very similar in the control cultures not treated with tunicamycin (Ctrl). (C) HeLa cells (26105/well) were cultured in 6-well plates for 24 h and then transfected with a control siRNA or C/EBP-b-specific siRNA. After 24 h, RNA was isolated and analyzed by RT-PCR (left panels), and cell extracts were prepared and analyzed by immunoblotting with antibodies directed to the common C- terminus of C/EBP-b (right panels). The gels and blots are representatives of three replicate experiments. (D) HeLa cells were seeded and transfected as described in (C). After 36 h, diluent (Ctrl) or Tunicamycin (Tm) were added and after an additional 31 h the cultures were stained with Crystal Violet and photo- graphed. The photographs are representatives of four replicate experiments. Bar = 0.5 mm. (E) Cell counts following the treat- ments described in (D). 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