Inactivation of Tsc2 specifically killed Rbf1-deficient cells in the Drosophila eye; induced cell death in RB1-mutant DU145 prostate cancer cells, Saos-2 osteosarcoma cells, and MDA-MB-468 breast cancer cells but not in their RB1-wild type counterparts; and inhibited tumor growth in nude mice [10,11]. Here, RB1 is linked to osteosarcoma.