Retinal Pigment Epithelial Cells Express a Functional Receptor for Glucagon-Like Peptide-1 (GLP-1)

Figure 6

Pharmacological inhibition of PI3K blocked GLP-1-induced activation of ERK1/2. ARPE-19 cells were cultured in serum-free medium for 24 hours and stimulated for 10 minutes with 10 nmol/L GLP-1 in the presence or absence of MEK1/2 inhibitor U0126 (10 μmol/l) or PI3K inhibitor LY294002 (50 μmol/l), or EGFR inhibitor AG 1478 (0.25 μmol/l). (a) Representative western blot analysis of ERK 1/2 phosphorylation (phERK1/2) and total protein is shown. (b) Quantification of densitometries of western blot bands of phERK1. Data were expressed as mean ± SE of fold induction relative to total ERK1 (𝑛=3). ^∗∗𝑃<0.01 versus cells stimulated with control medium alone. (c) Quantification of densitometries of western blot bands of phERK2. Data were expressed as mean ± SE of fold induction relative to total ERK2 (𝑛=3). ^∗∗∗𝑃<0.001 versus cells stimulated with control medium alone.