Importantly, PARPi treatment significantly increased γH2AX positivity following RB1 depletion in RB1-normal osteosarcoma CAL72 (Fig. 7b) or RB1-normal osteosarcoma 143B cells (Supplementary Fig. 7d–g), yielding a significant increase in the percentage of γH2AX-positive cell following depletion compared to their respective unmodified maternal lines (Supplementary Fig. 7c, h). The gene discussed is RB1; the disease is osteosarcoma.