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Table 2 Effect of Bax genotype on properties of myofibers in vivo.

From: Immortalization of mouse myogenic cells can occur without loss of p16INK4a, p19ARF, or p53 and is accelerated by inactivation of Bax

Property Muscle Bax-positive ave ± SE (n) Bax-null ave ± SE (n) Significance*
Cross-sectional area (μm2) of fast myofibers Soleus 1045 ± 17.0 (451) 785 ± 11.9 (500) P < 0.0001
  Diaphragm 873 ± 7.7 (1364) 717 ± 6.9 (1570) P < 0.0001
Cross-sectional area (μm2) of slow myofibers Soleus 1399 ± 33.7 (193) 1096 ± 16.6 (270) P < 0.0001
  Diaphragm 640 ± 15.0 (136) 547 ± 12.8 (150) P < 0.0001
Percentage of fast myofibers Soleus 70.2 ± 1.8 (3) 70.8 ± 0.1 (3) P > 0.7
  Diaphragm 90.7 ± 0.7 (5) 91.2 ± 0.8 (5) P > 0.7
Cross-sectional area (mm2) of whole muscle Soleus 1.54 ± 0.12 (4) 1.18 ± 0.06 (5) P = 0.024
Total number of myofibers Soleus 1081 ± 36 (4) 1102 ± 17 (5) P > 0.5
  1. Fast and slow myofibers were identified by ATPase staining as described in Methods. *Comparison of Bax-positive to Bax-null with unpaired, two-tailed, t-test.