For Ad-BMP9 infection, we used a recombinant adenovirus expressing BMP9 and demonstrated that this recombinant adenovirus is capable of efficiently transducing mBMSCs (Supplemental Figure S3), and found p21, Runx2 mRNA increased significantly 24 h post-infection (Figure 2E); 48 h after infection, the change in protein levels was the same as the change in mRNA levels, but the p53 level increased 24 h post-infection and then decreased (Figure 2F). This evidence concerns the gene GDF2 and infection.