Stimulatory effect of GHRH agonists on ERK, AKT, and cAMP/CREB pathways. (A) Stimulation of p-ERK/ERK and p-AKT/AKT after a 30-min treatment with MR-356 and MR-409. (B) Inhibition of MR-409-induced cell proliferation by PD98059 (PD, 25 µM) or Wortmannin (Wt, 0.5 µM). Data shown are a representative experiment done in quintuplicate in each treatment; *P < 0.05, **P < 0.01, ***P < 0.001. (C) Stimulation of cellular cAMP in MR-409-treated INS-1 cells. (D) Elevated pCREB/CREB in MR-409-treated INS-1 cells. Data were averaged from individual experiments. A representative Western blot image is shown.