pp90RSK activation is required for maximal transcription of the −116 CAT/egr-1 promoter construct.
TF-1 cells (107) were factor- and serum-starved for 24 hours, and placed in serum-free media. Twenty micrograms of −116 CAT/egr-1 construct, 20 μg of wild-type pp90RSK, and 20 μg of kinase-defective pp90RSK were electroporated into TF-1 cells and stimulated with either diluent control (PBS + 0.02% BSA) or rhGM-CSF (1 nmol/L) for 4 hours. Four micrograms of CMV β-galactosidase plasmid was cotransfected as the internal control for transfection efficiency. Fold induction represents percentage acetylation (by CAT assay) of constructs stimulated by GM-CSF divided by percentage of diluent-stimulated constructs. P values were determined by Student paired t test analysis. Data represent the average of 3 independent experiments; each transfection was performed in triplicate.
