Fig. 1. FoxM1 deficiency results in muscle atrophy and impairs muscle regeneration.

a The visual comparison of muscle mass of tibialis anterior (TA) in FoxM1 deletion mice compared with control mice at 2 or 8 months of age. b Quantification of TA weight/body weight in FoxM1^fl/fl and FoxM1-cKO mice at 8 months of age (n = 5). c, d Immunofluorescence of myonucleus on single myofiber by DAPI staining (c) and number count (d) (n = 6, 20 myofibers per mouse). Scale bar, 100 μm. e Hematoxylin and eosin (HE) staining of the TA muscle cross-sections in mice at 2 or 8 months of age. Scale bar, 100 μm. f Average cross-section area (CSA) of TA in FoxM1^fl/fl and FoxM1-cKO mice at 8 months of age (n = 10). g The maximum running distance (measured by a treadmill) of FoxM1-cKO mice compared with control mice at 8 months of age (n = 8). h A schematic illustration showing the experimental design for muscle injury. BaCl₂ was injected into and along the length of TA and gastrocnemius muscle of mice (2 months of age). The skeletal muscle or TA muscle was harvested at 7–30 days post-injury (DPI) depending on the experiments. i HE staining of the TA muscle cross-sections of FoxM1-cKO mice compared with control mice at 7 days and 14 DPI. Scale bar, 100 μm. j Average CSA of TA muscle in mice at 14 DPI (n = 5). Error bars represent the means ± SD. **p < 0.01, ***p < 0.001; Student’s t test.