PAX3 and infection: Infection of C2C12 cells with either Pax3DN RV or Pax7DN RV dominant-negative constructs led to a rapid (within 24 h) and significant (p<0.0001) reduction in the proportion of cells expressing either MyoD or myogenin protein (Figure 3d and e, quantified in p), suggesting that although all C2C12 cells lack Pax3, Pax transcriptional targets are normally activated.