Intraperitoneally administered β-elemene was reported to inhibit in vivo growth and metastasization of C57BL/6 mice carrying B16-F10 melanoma through downregulation of tumor promoting factors such as MMP-2, MMP-9, VEGF, urokinase-type plasminogen activator (uPA) and uPA receptor. The gene discussed is MMP9; the disease is neoplasm.