miR-218 inhibits the tumorigenicity of human osteosarcoma cells in vivo. (A) Statistical analysis of mean tumor weight calculated as follows: Weight=(weight1+weight2+weight3)/3. (B) Statistical analysis of tumor volume. (C) Representative images depicting PCNA-positive cells (scale bar, 20 µm; magnification, ×400). (D) Statistical analysis of the PCNA index. (E) Expression of E2F2 was verified using western blotting of tumor tissues from nude mice. (F) Quantification of relative expression level of E2F2 in miR-218, miR-218-sponge and control groups. miR, microRNA; PCNA, proliferating cell nuclear antigen. *P<0.05 and **P<0.01 compared with control group and miR-218 group; miR-218 and miR-218-sponge group.