We generated mouse models of osteosarcoma by disrupting Trp53 in combination with either SB transposon-mediated mutagenesis or concomitant loss of Rb1. We found that imprinting defects at 12qF, the homolog to the human 14q32 locus, were quite uncommon in SB-induced osteosarcoma. This evidence concerns the gene RB1 and osteosarcoma.