The maturation of miRs from primary miR precursors is tightly controlled by a few enzymes and regulatory proteins such as Drosha, Dicer, DiGeorge syndrome critical region 8 (DGCR8), Argonaute (AGO) proteins, and exportin-5, suggesting that the mutation or aberrant expression of those components of the miR biogenesis system provokes aberrant miR expression, which is associated with tumor progression. This evidence concerns the gene DICER1 and neoplasm.