Activation of AKT and ERK signaling after stimulation of cardiac stem cells with GHRH-R agonists. (A) Effect of AKT (AKT-X), PI3K (LY294002), and ERK (PD98059) pathway inhibitors on CSC proliferation after GHRH-R agonist exposure. Values represent incorporated BrdU 8 h after stimulation with agonists. Pathway inhibitors were tested at 5 μM and GHRH-R agonists at 100 nM. Error bars indicate SE (*P < 0.05, **P < 0.005, n = 5). OD, optical density. (B) Detection of phosphorylated ERK and AKT pathways 10 min after stimulation with vehicle control (DMSO) and GHRH-R agonists by ELISA. Values represent fold change relative to unstimulated cells before agonist treatment (n = 2).