Fig. 6.

Phosphorylated p42/p44 differentially influence PRB transcriptional activity. A, MDA-MB-231-PRB or Ishikawa PRB cells were transiently transfected with PRE₂-luciferase vector during 24 h, pretreated with dimethylsulfoxide (DMSO) or U0126 (10 μm) during 30 min, and then incubated with vehicle (Veh) or progesterone (P4) (10⁻⁸ m) or R5020 (R50) (10⁻⁸ m) or RU486 (RU) (10⁻⁸ m) during 24 h. Luciferase activity was determined and normalized to total protein concentration. The data (mean ± sem) from six independent cell cultures are set to 1 for ligand-free condition from DMSO or U0126-treated cells, and fold induction by hormone is presented. Statistical significance is shown by asterisks for ligand-induced transactivation as compared with vehicle or by XX when similar ligand condition is compared between DMSO or U0126-pretreated cells. B, MDA-MB-231 PRB cells were incubated with U0126 and hormones as above during 6 h, and quantitative real time PCR analysis was performed for indicated gene transcripts. The data (mean ± sem) from three independent cell cultures measured in duplicate are set to 1 for ligand-free condition from DMSO or U0126-treated cells, and fold induction by hormone is presented. Statistical significance is shown as in A. DKK1, Dickkopf homolog 1; AREG, amphiregulin; EREG, epiregulin; Sgk1, serum and glucocorticoid-regulated kinase 1. *, P ≤ 0.05; X, P ≤ 0.05; **, P ≤ 0.01; XX, P ≤ 0.01.