MSTN and rhabdomyosarcoma: Chimeric ASOs consisting of 2′-O-methyl RNA (2′-OMeRNA) and 2′-O,4′-C-ethylene-bridged nucleic acid (ENA®) were designed against exonic splicing enhancer sequences within exon 1 of the MSTN gene and were examined for their ability to reduce MSTN mRNA levels in CRL-2061 rhabdomyosarcoma cells that highly expressed MSTN mRNA.