EGF has been known for a long time as a mitogen for both UMR 106-01 cells, a rat osteosarcoma osteoblastic cell line, and primary calvarial osteoblastic cells.(29) In our past studies, we demonstrated that amphiregulin has strong proliferative effects on preosteoblasts and that EGFR signaling is important for normal growth of osteoblastic cells. The gene discussed is AREG; the disease is osteosarcoma.