The treatment of olaparib, a PARP inhibitor, and doxorubicin, genotoxic chemotherapeutic agent commonly used for the treatment of osteosarcoma, significantly inhibited the proliferation of U2OS, SaOS2, MG63, and KHOS/NP osteosarcoma cells in a dose- and time-dependent manner (Fig. 4). The gene discussed is PARP1; the disease is osteosarcoma.