Fig. 3.

S79/81A PR phospho-mutant is transcriptionally active. (A) HeLa cells were transiently transfected with wt PR-B, S79/81A PR, or empty vector. At 24 h following transfection, cells were starved for 18 h in serum-free medium and then treated with 10 nM R5020 for 60 min. Lysates were analyzed via Western blotting using p-S81, PR, and Erk1/2 antibodies. (B) HeLa cells were transiently transfected with plasmids expressing wt PR-B, S79/81A PR, or vector only, as well as a firefly PRE-luciferase reporter construct and Renilla expression control. At 24 h following transfection, cells were starved for 18 h in serum-free medium, followed by an 18-h 10 nM R5020 (or vehicle) treatment. Fold relative luciferase units (RLU; PRE-luciferase over Renilla luciferase controls) of R5020-treated cells over EtOH-treated cells is plotted. Error bars represent means ± standard deviations (SD) of results from three independent experiments.