PAX3 and neoplasm: This system was also used to drive Pax3::Foxo1 expression in embryonic muscle [under the Pax3-Cre (MCre) promoter], embryonic and fetal muscle (under Myf6-Cre), or postnatal satellite cells (under Pax7-CreER); overall, the embryonic and fetal muscle lineage had the highest penetrance and quickest tumor onset (Abraham et al., 2014).