Intriguingly, siRNA-mediated POLD1 depletion impaired proliferation and/or invasive potential, and increased genome instability of (liver, breast, cervical and osteosarcoma) cancer and normal cells [5, 29, 30], which confirmed the key role of POLD1 in cell cycle progression and DNA damage repair. This evidence concerns the gene POLD1 and osteosarcoma.