Additionally, tumor cells secrete growth factors, metalloproteinases, and proteases to migrate through the BBB, such as prostaglandin-endoperoxide synthase 2 (COX2), the heparin-binding EGF-like growth factor (HB-EGF), matrix metalloproteinases (MMPs), and cathepsin S [168]. The gene discussed is PTGS2; the disease is neoplasm.