These results are corroborated by the PCR and western blot analyses. The RT-PCR representative images ( Figure  6d ) and the qRT-PCR exon skipping results (Figure 6c ) both indicate reduced exon skipping in mdx mice treated with Pip6c-and Pip6d-PMO conjugates in quadriceps and diaphragm and negligible exon skipping in the heart. Western blot analysis revealed inefficient dystrophin protein production in the TA and quadriceps muscles and negligible dystrophin restoration in the heart (Figure 6e and Supplementary Figure S2b) .