miR-181a binds to the Prox1 3′-UTR, resulting in transcript repression. (A) Cross-species sequence alignment of the proposed miR-181 binding site located in the 3′-UTR (nucleotides 1-50 after the stop codon shown) of the Prox1 transcript. The miR-181 binding site is boxed and shaded. Con indicates conserved residues (100% conservation across species). (B) Luciferase reporter assay illustrating that miR-181a binds to the 3′-UTR of Prox1, resulting in transcript repression and reduced luciferase expression in HeLa cells. miR-181a does not repress luciferase activity when coexpressed with a Prox1 mutant construct in which the miR-181a binding site is mutated: Prox1 3′-UTR (mutant; mutated residues highlighted in bold and underlined). Renilla luciferase signal is normalized to the internal firefly luciferase transfection control; n = 6. **P < .001. Data are mean ± SEM. P values were calculated using Student paired t test.