Fig. 5.

Overexpression of glutamate receptor type 1 (GluR1) enhances focal adhesion kinase (FAK) activation and Rac1 signaling. (A) Overexpression of GluR1 led to increases in FAK phosphorylation (p-FAK) at tyrosine 397 (Tyr397; arrow) in U87 glioma cells overexpressing GluR1 (Over GluR1). (B) Rac1-GTPase activity was evaluated using a glutathione S-transferase–p21-activated kinase (GST-PAK) pulldown assay followed by immunoblotting with anti-Rac1 antibodies. Cells were starved and then stimulated with 50 μM α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) for the designated time. Results showed a time-dependent increase in Rac1 activation following AMPA receptor stimulation in cells overexpressing GluR1 and short hairpin RNA scrambled controls, which was blocked in U87 short hairpin GluR1 (shGluR1) cells. GTP, guanosine triphosphate; IP, immunoprecipitation; RBD, Rac1 binding domain; WB, Western blot. (C) Densitometry revealed the fold changes in Rac1 activity to be significant (*p < 0.05, Student’s t-test).