Rg1’s Effect on Senescence-Associated Protein Expression of BMSCs in Aged Rats. The BMSCs were collected on day 5 of passage 3. (A) Western blots showing β-actin, p16, p21, and p53 protein expression. (B) The integral optical density (IOD) values for p16, p21, and p53 proteins normalized to β-actin were calculated. a: comparison with the control group (p < 0.05); b: comparison with the D-gal-administration group (p < 0.05). Each error bar represents the standard deviation (SD).