Indeed, a comparison of oncolytic activity of double recombinant VVs in human and mouse tumor cells showed that MX-7 mouse rhabdomyosarcoma cells were less sensitive to both viruses, VV-GMCSF-Lact and VV-GMCSF-Apo, than MDA-MB-231 human adenocarcinoma cells. This evidence concerns the gene AOPEP and rhabdomyosarcoma.