Fig. 8.

S6K1 is dispensable for nascent myofiber formation but required for myofiber growth in muscle regeneration. WT, s6k1+/−, and s6k1−/− mice were subjected to TA muscle injury, muscle isolation, and H&E staining as described in Fig. 1. A: number of regenerating myofibers was counted within an area of 614,400 μm² for each sample. No statistically significant difference was found when comparing muscles of three genotypes at each time point. B: CSAs of regenerating myofibers were quantified. At least 100 regenerating myofibers were measured for each muscle section. The average results (n = 4 mice for each data point) are shown, with error bars representing SD. Two-way repeated measures ANOVA was performed to analyze CSA data over regeneration time and between different genotypes. Overall analysis: time, P < 0.0001; genotype, P < 0.0001; interaction, P = 0.26. Significant difference between genotypes at each time point: *P < 0.05, **P < 0.001. Significant difference between Day 28 AI and uninjured: †P < 0.05.