Figure 6.

Rsk-2 is not necessary for SRF phosphorylation. Normal (RSK2⁺) and CLS (RSK2⁻) cells that had been starved for 24 hr were treated with 20% fetal calf serum and 30 ng/ml of EGF for 10 min before preparing nuclear extracts. Three micrograms of nuclear proteins was used per lane. α-Phospho-SRF (α-P-SRF) antibodies were added to the equilibrium-binding reactions (lanes 3–5 and 6–8) for 10 min. The specific SRF/SRE complex is indicated by an arrow. The SRF/SRE/α-P-SRF super-shifted complex is indicated by an arrowhead. Lane 9: equilibrium-binding reaction was incubated with preimmune serum for 10 min before loading onto the polyacrylamide gel.