FIG. 2.

ei24 is an immediate-early wtp53 response gene. Murine 2a39 fibroblast cell lines harboring either the pBabepuro-only vector (pBabe) or expressing the conditional wild-type p53ER fusion protein (p53ER) were cultured under normal growth conditions (Cont) or treated with either 10 μg of cycloheximide (Cyclo) per ml, 100 μM Tam, or cycloheximide plus Tam (Cyclo/Tam) for the indicated times. Cells that were treated with both cycloheximide and Tam were preincubated with cycloheximide for 45 min to efficiently inhibit protein synthesis prior to activation of p53ER with Tam. Total RNA was isolated and analyzed by Northern blotting for ei24, p21cip1, and bax expression (top). RNA was stained with ethidium bromide prior to transfer and photographed to document equal loading of RNA (bottom).