Many molecular abnormalities are identified in osteosarcomas giving the cancer cells some particular characteristics: proliferative signals (PDGFR, IGFR, c-KIT), resistance to retroaction signals (p53, RB), resistance to cell death (ERK, Bcl-2), angiogenesis (VEGFR, PDGFR), resistance to immune destruction (IFN) [12]. The gene discussed is RB1; the disease is osteosarcoma.