Figure 5.

Increased expression of α7β1 integrin promotes hypertrophy. Cross-sectional areas of fibers in soleus and tibialis anterior muscles were measured. Using the largest fiber area in wild-type animals as a cutoff point (dashed line), α7BX2-mdx/utr^−/− mice were found to have four times more hypertrophic fibers than mdx/utr^−/− mice. Thus increasing the level of integrin promotes a hypertrophic response that contributes to the rescue of these animals. The cross-sectional areas of 200 to 300 fibers from each muscle were measured for each of four animals per genotype.