S100A4 expression has been reported to induce the expression and secretion of OPN in osteosarcoma cells through the NF-κB-dependent signaling, while extracellular S100A4 mediates OPN-dependent induction of proteolytic activity, which further increases osteosarcoma cell invasion and metastasis as well as angiogenesis [151]. The gene discussed is S100A4; the disease is osteosarcoma.