RBL2 and osteosarcoma: Indeed, it has been suggested that the difference in apoptotic response to chemotherapeutic treatment observed in drug-resistant osteosarcoma cells and their parental cell line could be due to the presence of distinct E2Fs–RBL2/p130 complexes on the p73 promoter: in the parental cell line, p73 transcription is activated by an E2F1–RBL2/p130–p300 complex, whereas, in the drug-resistant cells, it is repressed by an E2F4–RBL2/p130–HDAC1 complex [100].