Several factors suggest that miR-21 may be impacting matrix metalloproteinases inhibitors, such as TIMP3, that play a crucial role in cancer invasion and metastasis[23] including recent studies that identified TIMP3 as a functional target of miR-21 in cell invasion and metastasis in glioma and cholangiocarcinoma[15,16]. The gene discussed is TIMP3; the disease is central nervous system cancer.