Figure 3.

Mitogen stimulation results in Ser-246 phosphorylation in vivo. SAOS2 human osteosarcoma cells ectopically expressing the rat wt GR (25) were serum-starved for 48 h in 0.1% FBS/DMEM. The receptor was metabolically labeled for 4 h with 1 mCi/ml of [³²P]orthophosphate and 100 nM Dex, in the absence (− serum) and presence (+ serum) of 10% FBS. In vivo labeled receptor was immunoprecipitated from cell lysates with the GR-specific monoclonal antibody, BuGR2 (26), and subjected to two-dimensional phosphopeptide mapping.