Nobiletin suppresses the expression of matrix metalloproteinases 1, 3 and 9, which participate in the break down of the extracellular matrix during tumor metastasis. Nobiletin is also involved in the increased expression of tissue inhibitor of matrix metalloproteinase 1 further preventing extracellular matrix degradation during tumor invasion. This bioflavonoid is believed to achieve both of these functions by disrupting the signal transduction pathway of Ras-Raf-MEK.