Involvement of Akt in SWT extract-induced bone mineralization in osteoblasts. (A) Cells were seeded in 24-well plates and cultured for 2 wks in medium containing vitamin C (50 μg/mL) and β-glycerophosphate (10 mM). The cells were concomitantly treated with SWT extract (150 μg/mL) plus Akt inhibitor. Mineralized nodule formation was assessed by alizarin red-S staining. (B) Cells were incubated with SWT extract (150 μg/mL) plus Akt inhibitor for 72 h, and ALP was measured with an ALP activity assay kit. (C) Cells were pretreated with Akt inhibitor for 30 min or transfected with Akt siRNA for 24 h followed by stimulation with SWT extract for 24 h, and ALP, BMP-2, and OPN mRNA expression was measured by qPCR. (D) Cells were treated with SWT extract for the indicated time intervals, and p-Akt expression was examined by western blotting. *, p < 0.05 compared to the control group; #, p < 0.05 compared to the SWT extract-treated group.