Figure 7. SP can restore impaired function of BMSC due to osteoporosis. (A) Experimental scheme for direct actions of SP on BMSC in vitro. (B) Cell viability was measured by WST-1 assay. (C) Population doubling time (PDT) of BMSC was calculated. (D) p-Akt, t-Akt, p-Erk and t-Erk protein levels were determined by western blot and their expression levels were quantified using the Image J program, relative to the GAPDH. (E) Osteogenic differentiation was exerted by BMSCs and determined by alizarin red staining. (F) TGF-β1, OPG and HGF protein expressions in BMSC were elucidated by western blots and quantified relatively. p values of less than 0.05 were considered statistically significant (* p <0.05, ** p <0.01, *** p <0.001). The data are expressed as the mean ± standard deviation (SD) of three independent experiments. OPG: osteoprotegerin, HGF: hepatocyte growth factor. n = 5/ experimental setting.