Fig. 2.
GM-CSF stimulates pp90RSK activation and CREB phosphorylation.
TF-1 cells (2 × 107 per time point) were serum- and factor-starved for 24 hours, and stimulated with rhGM-CSF (1 nmol/L) for 2, 5, 10, 15, 30, and 60 minutes, and with diluent for 10 minutes as negative control (BSA + 0.02% in PBS). TPA (50 ng/mL) served as the positive control. Cell lysate (600 μg) was immunoprecipitated with anti-RSK antibody (2 μg per sample). (A) Immune complex kinase assays were performed with affinity-purified GST-CREB (11 μg per sample). The arrow indicates the location of GST-CREB (63 kd). (B) Phosphorylation was quantitated by scintillation counting. The results represent 1 of 3 separate experiments.
