Reflecting this general function of miRNAs, we observed significantly increased expression of 548 tumor cell mRNAs from the platelet miRNA-depleted mice, 321 of which harbor miRNA recognition elements for the 44 most depleted miRNAs in Dicer1-deleted platelets, indicating that platelet miRNAs are necessary to modulate expression of these genes. This evidence concerns the gene DICER1 and neoplasm.