Pip6a is an arginine-rich cell-penetrating peptide that facilitates the transport of drugs across plasma and endosomal membranes. It consists of a hydrophobic core flanked by arginine-rich domains containing β-alanine and aminocaproic acid spacers. When Pip6a is combined with morpholino phosphorodiamidate oligomer (PMO), it significantly enhances the delivery of antisense oligonucleotides (ASO) to the striated muscle of myotonic dystrophy type 1 (DM1) mice.