Fig. 5

The increased extents of activations in p38, ERK1/2 and PI3K/Akt were different between 15% stretched L6 and C2C12 myoblasts (a) and transfection L6 cells with AR overexpression plasmid further enhanced the above molecules' activities (b and c). a Myoblasts C2C12 (with AR) and L6 (no detectable AR) were seeded onto flexible-bottomed 6-well plates and incubated for 24 h prior to 15% stretch. Then cells were collected and the activities of PI3K/Akt, p38 and ERK1/2 (reflected as the ratios of p-PI3K/PI3K, p-Akt/Akt, p-p38/p38 and p-ERK1/2/ERK1/2, respectively) were detected at 24 h after stretch finished. The promoted degrees in the activities of PI3K and MAPKs (p38 and ERK1/2) were calculated by the following formula: = (the activities of PI3K/Akt and MAPKs (p38 and ERK1/2) _{15% stretch}—the activities of PI3K/Akt and MAPKs (p38 and ERK1/2) _CON)/ the activities of PI3K/Akt and MAPKs (p38 and ERK1/2) _CON. * indicated p < 0.05 vs. C2C12 cells. b and c L6 myoblasts were seeded onto flexible-bottomed 6-well plates one day before transfection, and when the confluence reached ~ 50%, pcDNA3.1 vector or pcDNA3.1-AR overexpression plasmid (2.5 μg/well) was transfected before exposing to 15% stretch, and the activities of PI3K/Akt, p38 and ERK1/2 were detected by Western blot at 24 h after stretch finished. *p < 0.05 vs. CON_pcDNA3.1; ^#p < 0.05 vs 15% stretch_pcDNA3.1. The differential values resulting from three independent experiments were compared (mean ± SD, n = 3)