Fig. 3.

HER2 expression increased by short-time incubation with E2, independently of de novo protein synthesis. HER2 mRNA levels were measured in 0.25-h intervals and 3, 6, 9 or 24 h of incubation with low (1 nM; a) or high (100 nM; b) E2 concentrations (white bars). At 3 h of incubation with 1 nM E2, HER2 mRNA levels increased up to twofold in the absence and presence of the de novo protein inhibitor cycloheximide (CHX; 12.5 μg/ml, black bars) and decreased at 6 h of E2 incubation. Long-time incubations (9–24 h) with E2 increased HER2 mRNA, an effect that depended on de novo protein synthesis. There were no differences between low and high concentrations of E2. Results are expressed as percent of HER2/actin vs. control (Vh) cells (mean ± SD). *P < 0.05 vs. control. Representative images of at least three independent experiments are shown