MMP9 and neoplasm: RNAi-mediated silencing of MMP9 in B16 mouse melanoma cells significantly reduced migration and invasion, and furthermore, intratumoral injection of MMP9 siRNA into a C57BL/6 mouse tumor model resulted in the inhibition of tumor growth and reduced lung and liver metastasis, indicating MMP9 as a potential therapeutic target for malignant melanoma [188].