SMAD4 and neoplasm: Taken together, these studies support the idea that downregulation of miR-34a-3p, especially in higher-grade meningiomas, may contribute to EMT, increased cell proliferation, invasion and migration of tumor cells via loss of translational repression of SMAD4. This scenario is consistent with our result that shows decreased meningioma cell proliferation in vitro as result of overexpression of miR-34a-3p.