mmu-miR-378a-5p agomirs are chemically-modified double-strand miRNA mimics with modified mature miRNA strand: 2 phosphorothioates at the 5′ end, 4 phosphorothioates at the 3′ end, 3′ end cholesterol group, and full-length nucleotide 2′-methoxy modification. They are designed to mimic endogenous miRNAs and recommended for miRNA functional studies. Compared with miRNA mimics, they exhibits enhanced cellular uptake, stability and regulatory activity in vivo.