PAX3 and infection: In contrast to the ability of ectopic PAX3-FOXO1A [34], Pax3 and Pax7 were unable to induce each other, or myogenic proteins, in NIH 3T3 fibroblasts maintained under expansion conditions, as reported elsewhere [41] (although specific culture conditions can produce limited activation of the myogenic program after Pax3 infection [41]).