Skeletal muscles from FSHD-like mouse models develop centralized nuclei. Soleus and TA muscle histological sections from control ACTA1-MCM (blue) and mild (green), moderate (yellow), and severe (red) FSHD-like model mice that had undergone treadmill exhaustion analysis 2× per week (see Figs. 7 and 8), were stained with H&E and counted for myofibers with centralized nuclear. Muscles were assayed at the indicated time points for each model. The ACTA1-MCM +TMX controls were assayed at MD28 and SD9, as appropriate. Data is plotted as percent of myofibers with centralized nuclei. Data are mean ± S.D. with significance calculated by one-way ANOVA using Prism 7. *p < .05, **p < .01, ***p < .001, #p < .001 for ACTA1-MCM compared with all other samples in the group.