To investigate if selective PARPi sensitivity in RB1-mutant osteosarcomas is a consequence of RB1 loss, we depleted RB1 in RB1-normal osteosarcoma lines CAL72 or 143b using multiple RB1-targeting small-hairpin RNAs (shRNA) (Fig. 4 and Supplementary Fig. 4). This evidence concerns the gene RB1 and osteosarcoma.