Osteosarcoma is the most common type of bone cancer. Although stage I osteosarcoma has a promising prognosis, stage III osteosarcoma with lung metastases with only about 30% survival rate is worrying. Expression of EGFR and its downstream proteins has been regularly observed in osteosarcoma. In this book, the main focus is on two major aims: 1.Analysis of the role of EGFR signaling during bone tumor formation by breeding H2-c-fosLTR transgenic mice, that develop OS with 100% penetrance, to mice that harbor either reduced (Egfrwa2/wa2) or elevated (Col1-AREG) EGFR signaling; 2.Analysis of the effect of EGFR inhibition on proliferation, viability and apoptosis as well as on EGFR downstream signaling proteins in c fos transgenic osteosarcoma cells.