Using an animal model of DMD, the mdx mouse (which carries a premature stop codon in dystrophin exon 23), and a dystrophic mouse cell culture line carrying the mdx mutation (H2KSF127), we combined the well-established mdx-specific skipping oligo (M23D)28 with PMOs representing “sponge”, “protector” and “miR31-analogue” sequences (schematic: Fig 1 B-E, sequences and hybridization scheme in supplementary fig S1). The gene discussed is DMD; the disease is Duchenne muscular dystrophy.