FIGURE 4.
Signaling mechanism involved in INT-777-induced increased PC1 expression in α cells. A, PC1 promoter activity in αTC1-6 cells treated with or without INT-777 in the presence (+) of Gαs inhibitor (NF449, 10 μm) or PKA inhibitor (Myr-PKI, 1 μm). Immunoblot analysis was performed for phosphorylated and total CREB (pCREB and CREB) in αTC1-6 cells (B) and db/db mouse islets (C) treated with or without INT-777. Bar graphs show the densitometric values calculated after normalization to CREB. G, glucose. Data are expressed as the mean ± S.E. of three or four experiments. *, p < 0.05, compared with 5 mm glucose basal; **, p < 0.001, compared with 25 mm glucose basal.