FIGURE 1.

Inducible FGFR2 homodimerization system stimulates tyrosine and Erk1/2 phosphorylation. A, schematic representation of the FGFR2 activation system. The AP20187 synthetic ligand binds to two FKBP domains located on the inner face of the plasma membrane. Ligand binding induces fusion protein dimerization and activates FGFR2 kinase domains to initiate downstream signal transduction. B, plasmid constructs for generation of FGFR2 FKBP activation system and imunocytochemistry staining of ES cell clones that stably express FGFR2 FKBP activation system using an anti-HA antibody. Scale bar, 100 μm. C and D, ES cells stably expressing FGFR2 homodimerization system were treated with or without AP20187 (10 nm) over a time course (15 min to 3 h). Immunoblotting was performed using anti-phosphotyrosine and β-actin control antibodies (C) or anti-phospho-p90RSK, Akt, Erk1/2, S6, and control eIF4E antibodies (D). CAG, cytomegalovirus early enhancer/chicken β-actin promoter; MW, molecular weight; Myr, myristoylation signal; IRES, internal ribosome entry site.