The results of the RT-PCRs and the qPCR indicate that transfection with the mixmers at 5 nM induces nearly 100% exon 7 inclusion in SMA fibroblast cells (Figs 2 and 3), whereas 2′MOE oligos (nusinersen) were reported to induce the exon inclusion at 100 nM in vitro 28. The effective concentration for the mixmer transfection is also lower than that of the PMO transfection (100 nM)27. Additionally, the results indicate that the 13-mer AONs are sufficient to target ISS-N1 and induce the exon inclusion whereas the 8-mer AONs are not, corresponding to the previously published data with 2′OMeP AONs18, 29. The ISS-N1 has two hnRNP A1 binding sites7, 29. The 8-mer AONs block only one of these sites, while the 13-mer AONs cover the one and more than half of the other sites. These indicate that both hnRNP A1 binding sites should be targeted by AONs to induce exon inclusion.