We found that both E43′ and E45′ SSOs were able to cause skipping of exon 4 as confirmed by RT-PCR and sequencing of PCR products, which demonstrated the absence of exon 4 sequences in the smaller PCR product obtained from the SSO-treated ERG-positive PCa VCaP cell line, as well as the ERG-positive osteosarcoma MG63 cell line. This evidence concerns the gene ERG and osteosarcoma.