SDC4 and muscular disease: Consistent with the previous report (Cornelison et al., 2004), we did not observe any centrally nucleated myofibers in the syndecan-4–/– (Supplementary Figure 1A), a characteristic often associated with muscle disorders (Cornelison et al., 2004; Folker and Baylies, 2013) and impaired maintenance of MuSC quiescence (Pisconti et al., 2016).