Effects of NMDA receptor activation on ERK signaling in BM-MSCs. (A) BM-MSCs were treated with 3 and 10 mM NMDA for 24 h, or were pre-incubated with 50 μM MK801 for 30 min prior to 10 mM NMDA treatment. Protein expression levels of P-ERK1/2 and ERK1/2 were detected in BM-MSCs by western blotting. Data are presented as the means ± standard error of the mean, n=3. *P<0.05, **P<0.01, ***P<0.001 vs. control; #P<0.05 vs. 10 mM NMDA. (B and C) BM-MSCs were treated with 10 μM Honokiol (ERK1/2 activator) or FR180204 (ERK1/2 inhibitor), for 30 min prior to treatment with 3 mM NMDA for 24 h. HGF protein expression and secretion in BM-MSCs was detected by western blotting and ELISA, respectively. Data are presented as the means ± standard error of the mean, n=3. **P<0.01 vs. control; #P<0.05, ##P<0.01 vs. NMDA. BM-MSCs, bone marrow-derived mesenchymal stromal cells; ERK, extracellular signal-regulated kinase; HGF, hepatocyte growth factor; NMDA, N-methyl-D-aspartate; P-, phosphorylated.