Figure 3.

Effect of 10 nM recombinant sAPP on the stimulation of MAP kinase activity in the absence of TSH. Detection of ELK-1 fusion protein by immunoblot analysis using a phospho-ELK-1-specific antibody showed a significant increase in Elk-1 phosphorylation after the addition of 10 nM sAPP for 10 min as compared with untreated control cells. The stimulatory effect of 10 nM sAPP was determined radiometrically by the use of [γ-³²P]ATP and radiolabeled ELK-1 fusion protein. The control value was set as 1.