PAX3 and infection: NIH 3T3 cells infected with the control RV did not contain immunodetectable levels of Pax3 or Pax7 (Figure 6c) and infection with Pax3 RV or Pax7 RV did not result in myogenic conversion, as assessed by the absence of MyoD (Figure 6a–b′), myogenin and MyHC proteins, and a failure to form myotubes (data not shown).