To examine the effects of EGR1 up-regulation after anti-tumour agent treatment in modulating the invasive activity of osteosarcoma cells, in vitro invasive activity assays were performed to assess the proportion of osteosarcoma cells transfected with EGR1 expression vector or control vector that invaded through matrigel-coated membranes. The gene discussed is EGR1; the disease is neoplasm.