Sal induces activation of ERK1/2 and PI3K/Akt signaling pathways. (A and B) Human periodontal ligament cells were treated with Sal (0, 10, 20 or 50 µM) for 48 h and expression levels and phosphorylation status of ERK1/2, PI3K and Akt were determined using western blot analysis. *P<0.05; **P<0.01 vs. control. Sal, salidroside; ERK, extracellular signal-regulated kinase; PI3K, phosphoinositide-3 kinase.